Turn the forked slack-mcp-server into a CLI so running many agents no
longer means one resident MCP process each. Every command is a
short-lived process that reads the shared on-disk cache.
- rename module to github.com/paymog/slack-cli (go install/homebrew/ldflags)
- internal/toolcall: invoke the upstream tool handlers in-process; the only
mcp-go coupling lives here, so pkg/handler and pkg/provider are reused
byte-for-byte (clean upstream merges, fork-and-extend)
- internal/{cli,cmds,config,credstore,runtime,output}: cobra command tree,
keyring-backed credential profiles, provider bootstrap, result printing
- 21 tools as subcommands (channels, conversations, users, usergroups,
saved, reactions, attachments, cache); write tools keep their env gating
- goreleaser + homebrew release workflow; ships a skills/slack-cli skill
- unit tests for config/credstore/toolcall; MCP server still builds
The MCP server (cmd/slack-mcp-server) is kept intact.
When emails are forwarded to Slack channels, message content is stored in
files[] with filetype "email" rather than in text or blocks. This adds
FilesToText() to extract From, CC, and Subject metadata as a fallback
when msg.Text is empty, so these messages no longer appear as blank rows
in conversations_history output.
Closes#191
When a user ID is not in the in-memory cache, message rendering
degrades to raw IDs and paramFormatUser fails the tool call
entirely. This is common on Enterprise Grid workspaces where the
user cache (50K+ users) can be hours stale.
On cache miss, fetch the single user via users.info and patch the
snapshot atomically. This costs one API call instead of rebuilding
the entire user cache. Disk persistence is skipped; the next full
refresh cycle handles it.
Fixes#268
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Add optional `blocks` parameter to conversations_add_message for raw
Slack Block Kit JSON support (rich_text lists, code blocks, etc.).
When blocks is provided it takes precedence over text/content_type for
message rendering. The text parameter serves as notification fallback.
The blocks argument accepts both a JSON string and a raw JSON array to
accommodate different MCP client serialization behaviors.
Also bumps takara2314/slack-go-util from v0.3.0 to v0.4.0 which adds
nested list support to the existing text/markdown conversion path.
The handler was re-fetching the just-posted message via conversations.history
and returning it as CSV. Slack's history endpoint has propagation lag, so when
the message wasn't yet indexed the response was a header-only CSV with no data
rows, which confused LLM clients into thinking the post had failed.
Drop the follow-up history call and return a short success string with channel
and ts (matching ReactionsAddHandler). This removes the race entirely and
saves a tier3 API call per post.
Signed-off-by: Seena Fallah <seenafallah@gmail.com>
Previously, the AttachmentIDs field only contained raw file IDs
(e.g. "F08ABC1234"), making it impossible to identify which file
an ID corresponds to without calling attachment_get_data first.
Now the field includes filenames: "F08ABC1234 (contract.pdf)".
This makes it practical to use AttachmentIDs to selectively
download relevant attachments.
Fixes#260
The Slack search API returns both Channel.ID and Permalink on every
SearchMessage, but the MCP server was only using Channel.Name (formatted
as '#channel-name') and discarding the rest. This made it impossible for
LLM agents to construct valid Slack permalink URLs.
- Add Permalink field to Message struct
- Include msg.Channel.ID in the Channel column (format: 'C0515UGHR0R (#channel-name)')
- Pass through msg.Permalink from the Slack API response
Addresses korotovsky/slack-mcp-server#100.
SearchContext was the only Slack API call in conversations.go without
rate limiting or retry logic. Under concurrent load (e.g. parallel
searches across multiple workspaces), this caused immediate failures
when hitting Slack's Tier 2 rate limits.
Wrap the call with limiter.CallWithRetry using a Tier2 rate limiter,
matching the established pattern used by GetConversationHistoryContext
and GetConversationInfoContext in the same file.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Previously, attachment_get_data returned image files as base64-encoded
strings inside a JSON text response. For typical images (100-200KB),
the base64 expansion produces 130-270KB of text that exceeds MCP client
token limits, forcing clients to save overflow to temp files and manually
decode base64 — defeating the purpose of the tool.
Use the MCP SDK's NewToolResultImage to return images as native image
content, which MCP clients can render directly. File metadata (file_id,
filename, mimetype, size) is returned as the text component. Non-image
binary files retain the existing base64-in-text behavior.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add two new MCP tools for channel membership management:
- conversations_join: Join public channels via conversations.join API.
Idempotent — joining a channel you're already in is a no-op.
Requires channels:join (xoxb) or channels:write (xoxp) scope.
- conversations_leave: Leave channels, group conversations, or DMs
via conversations.leave API. Marked as destructive.
Requires channels:manage (xoxb) or channels:write (xoxp) scope.
On Enterprise Grid with session tokens (xoxc/xoxd), routes through
the edge API to bypass enterprise_is_restricted errors.
Both tools accept channel IDs (Cxxxxxxxxxx) or names (#channel-name)
using the existing resolveChannelID helper.
Updated docs/01-authentication-setup.md with new OAuth scopes
(channels:join, channels:manage) and docs/03-configuration-and-usage.md
with the new tool names in the available tools list.
Switch the xoxp unread scan from conversations.list to users.conversations.
users.conversations returns only channels the calling user is a member of,
eliminating non-member public channels and closed DMs that cannot have unreads.
Empirically tested on a 2700-channel workspace:
- 37% fewer channels to scan (1724 vs 2737)
- 85% reduction for public channels (156 vs 1046)
- Zero real unreads missed (verified against client.counts ground truth)
- Both methods return identical channel sets for member channels
- The 10 'missed' channels are all archived with never-visited markers
The includeMessages loop in getUnreadsViaConversationsInfo calls
GetConversationHistoryContext with no rate limiter and no retry — the
only conversations.history call in the xoxp path not wrapped in
CallWithRetry.
When include_messages=true and multiple unread channels are found,
these calls fire unthrottled, risking 429s that silently skip channels
and lose messages.
Fix: add a local Tier 3 rate limiter and wrap in CallWithRetry,
matching the pattern used everywhere else in the xoxp scan path.
The xoxp fallback in conversations_unreads calls GetConversationInfoContext
per channel to check for unreads. slack-go's standard Client does NOT
auto-retry on HTTP 429 — it returns *slack.RateLimitedError to the caller.
The scan loop handled ALL errors with continue at Debug level, so rate
limit errors were silently swallowed, causing non-deterministic results
(niebloomj confirmed 279/400 channels hit rate limits on their workspace).
This commit adds:
- limiter.CallWithRetry[T] generic helper in pkg/limiter: proactive
rate.Limiter.Wait + retry via caller-provided retryAfter callback
(no slack-go dependency in the limiter package)
- slackRetryAfter helper in the handler to extract RetryAfter from
*slack.RateLimitedError
- Applied to both GetConversationInfoContext and
GetConversationHistoryContext in scanTypeGroupForUnreads
- rateLimited counter surfaced in scan metadata so the LLM response
includes a WARNING when channels are skipped
- Rate limit errors promoted from Debug to Warn level
- 8 unit tests in pkg/limiter covering retry logic, exhaustion,
context cancellation, and typed return values
* fix: pre-check token type to avoid faulty ClientCounts call
client.counts only works with browser session tokens (xoxc/xoxd). OAuth
tokens (xoxp) get 'not_allowed_token_type' and bot tokens (xoxb) have no
concept of user-level unreads.
Instead of calling ClientCounts and catching the error after the fact,
pre-check the token type using the existing IsOAuth()/IsBotToken()
infrastructure and route directly to the appropriate path:
- xoxc/xoxd: fast path via client.counts (unchanged)
- xoxp: conversations.info fallback (no wasted API call)
- xoxb: clear error message
Follows the same pattern used by SearchUsers and GetConversationsContext
which already branch on token type.
Addresses review comments on korotovsky/slack-mcp-server#171.
* fix: exclude conversations_unreads tool for bot tokens
Bot tokens (xoxb) don't support unread tracking — it's a user-level
concept. Don't register the tool at all for bot token users, matching
the same pattern used for conversations_search_messages.
This gives a clean UX: bot users simply don't see the tool, rather
than getting a runtime error.
* fix: cap xoxp fallback scan depth and document limitations
The xoxp path previously scanned ALL channels (~2000+ API calls on large
workspaces). Slack's API has no bulk unread endpoint for xoxp tokens —
every other open-source implementation (agent-kit, NextNotifier, wee-slack)
uses the same per-channel scanning approach.
Changes:
- Cap scan depth to budget*2 per type group (~300 API calls max with
default max_channels=50, down from ~2000+)
- Return scan metadata (channels scanned, API calls) from each type group
- Prepend an xoxp limitation note to response text so the LLM knows
results may be partial
- Update tool description to explain xoxc vs xoxp behavior
- Fix inaccurate comment about conversations.list sort order
* fix: validate GetMutedChannels response to surface xoxp failures
Add validate() call after ParseResponse in GetMutedChannels (prefs.go),
matching the pattern used in ClientCounts. Without this, xoxp tokens
receive {ok:false, error:missing_scope} but ParseResponse only checks
HTTP status — the error was silently swallowed, returning nil/nil.
This caused muted channels to leak into xoxp results (17/28 channels
were muted in testing). Now the error propagates to the handler's
existing warn-and-proceed logic.
Also surface the limitation in the xoxp response note so the LLM
knows muted filtering is unavailable.
* fix: add shouldAddTool gating for conversations_unreads and conversations_mark
Both tools were missing Tool* constants, ValidToolNames entries, and
shouldAddTool() wrapping — breaking the established pattern used by
every other tool in the server. This prevented selective enable/disable
via the enabledTools config.
Also fixes indentation on conversations_mark registration block.
* fix: use index-based range loop so unread counts persist
The message-fetch loop uses 'for _, uc := range unreadChannels', so
writes to uc.UnreadCount go to a copy — the original slice element
stays at 0. Messages are fetched correctly (appended to a separate
slice), but the unread count column is silently wrong.
Switch to 'for i := range' and index into the slice directly.
Also aligns struct field formatting (gofmt).
* feat: backfill unread counts via conversations.history
client.counts returns HasUnreads (bool) and MentionCount per channel,
but MentionCount is only non-zero for @mentions. Regular channel
activity shows as 'has unreads' with count 0.
For channels where HasUnreads=true and MentionCount=0, call
conversations.history(oldest=lastRead, limit=20) to count actual
unread messages. DMs don't need this since every message counts
as a mention.
* feat: filter muted channels from unreads by default
Fetches muted channel set from users.prefs.get (all_notifications_prefs)
and excludes them from both ClientCounts and conversations.info fallback
paths. Adds include_muted opt-in parameter to show muted channels when
explicitly requested.
Muted status is only available in users.prefs.get as a nested JSON
string — it is not exposed by client.counts, conversations.info, or
conversations.list.
- Extract handler params to structs with parsing functions
(unreadsParams, markParams) following existing patterns
- Add SLACK_MCP_MARK_TOOL env var guard for conversations_mark
(disabled by default, requires explicit opt-in)
- Remove unused categorizeChannel and getChannelDisplayName functions
- Update README with conversations_mark safety note and env var docs
- Add IsExtShared field to Channel struct in cache
- Pass IsExtShared through mapChannel function
- Use cached.IsExtShared to identify external/partner channels
instead of checking for ext-/shared- name prefixes
Note: Users may need to delete their channels cache file to repopulate
with the new IsExtShared field.
- Add mentions_only parameter to conversations_unreads to filter
channels to only those with @mentions (priority inbox)
- Add conversations_mark tool to mark channels/DMs as read
- Supports channel IDs, #channel names, and @username
- If no timestamp provided, marks all messages as read
- Switch from ClientUserBoot to ClientCounts API
- ClientCounts returns HasUnreads boolean for all channels
- Add ClientCounts to SlackAPI interface
- Process Channels, MPIMs, and IMs separately
- Uses ClientUserBoot to get all channels with LastRead/Latest in one API call
- Filters channels where Latest > LastRead to find unreads
- Prioritizes: DMs > group DMs > partner channels (ext-*) > internal
- Only fetches message history for channels with actual unreads
- Supports filtering by channel type and configurable limits
Addresses issue #114
Resolve conflict in README.md by keeping updated env var descriptions
that document the SLACK_MCP_ENABLED_TOOLS interaction.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Merge shouldAddTool and shouldAddWriteTool into single function
- Remove redundant comments
- Add envVarName parameter for write tools requiring explicit enablement
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Write tools (conversations_add_message, reactions_add, reactions_remove,
attachment_get_data) now require explicit enablement:
- If ENABLED_TOOLS explicitly includes the tool, register it
- If ENABLED_TOOLS is empty, only register if tool-specific env var is set
- If ENABLED_TOOLS excludes the tool, don't register
This resolves the conflict where ENABLED_TOOLS="" would register all tools
but SLACK_MCP_ADD_MESSAGE_TOOL="" would fail at runtime with an error.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
The parameter name was inconsistent with the error message which said
"text must be a string". Changed to use "text" as the primary parameter
name with backward compatibility for "payload".
Fixes#181
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Messages using Slack's Block Kit format (emails forwarded via Slack,
bot notifications from Grafana/Datadog, app messages) return empty
text when retrieved via conversations_history. This extracts text
from block structures so these messages are no longer empty.
Closes#186
The isChannelAllowedForConfig() function had inverted return logic.
When a channel was NOT found in the list, it returned the opposite
of what was intended:
- Allowlist mode incorrectly allowed unlisted channels
- Blocklist mode incorrectly blocked unlisted channels
Fixed by changing 'return !isNegated' to 'return isNegated'.
Added unit tests for isChannelAllowedForConfig().
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
For xoxp/xoxb tokens, search the local users cache using regex matching
on username, real name, display name, and email. Browser tokens (xoxc/xoxd)
continue using the edge API for real-time search.
Adds a new users_search tool that searches for Slack users by name,
email, or display name using the Edge API. Returns user details
including UserID, username, real name, display name, email, title,
and DM channel ID (if available in cache).
Note: This feature requires browser session tokens (xoxc/xoxd),
not OAuth tokens (xoxp/xoxb), similar to conversations_unreads.
Fixes the issue where newly created Slack channels aren't discovered
until the MCP server is restarted.
Key changes:
- Add configurable cache TTL via SLACK_MCP_CACHE_TTL env var (default 1h)
- TTL uses file mtime so it survives server restarts correctly
- Add refresh-on-error: when channel lookup fails, refresh cache and retry once
- Add rate limiting via SLACK_MCP_MIN_REFRESH_INTERVAL (default 30s)
- Use atomic.Pointer[T] for cache maps to eliminate GC pressure on reads
- Thread-safe implementation with proper mutex protection
The refresh-on-error flow:
1. Channel name lookup fails (not in cache)
2. Force refresh channels from Slack API (rate-limited)
3. Retry lookup once
4. Return error if still not found
Performance optimizations:
- Cache config parsed once at init, not on every refresh
- Atomic pointer swap for map access (no copying on reads)
- Skip redundant lookup when rate-limited
- Single lock scope for rate limit check (prevents TOCTOU race)
Env vars:
- SLACK_MCP_CACHE_TTL: Cache duration (e.g., "1h", "30m", "3600", "0" to disable)
- SLACK_MCP_MIN_REFRESH_INTERVAL: Min time between forced refreshes (e.g., "30s")
Previously, messages with SubType "thread_broadcast" (i.e., threaded
replies sent with "also send to channel") were being filtered out by
the convertMessagesFromHistory function. This caused conversations_replies
to return incomplete results when a thread contained broadcast replies.
The existing filter excluded all messages with a non-empty SubType except
"bot_message". This change adds "thread_broadcast" to the allowlist,
ensuring broadcast replies are included in thread results.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Tool: files_get → attachment_get_data
- Field: FileIDs → AttachmentIDs
- Env var: SLACK_MCP_FILES_TOOL → SLACK_MCP_ATTACHMENT_TOOL
Per maintainer feedback - aligns with Slack's 'attachment' terminology
and may improve LLM performance due to training data prevalence.
Adds ability to download file content by file ID, addressing maintainer
request on PR #170.
- New files_get tool gated by SLACK_MCP_FILES_TOOL env var
- Text files (text/*, application/json, etc.) returned as plain text
- Binary files returned as base64-encoded content
- 5MB size limit to keep responses reasonable for LLM context
- Returns structured JSON: file_id, filename, mimetype, size, encoding, content
Adds metadata fields to help identify media-containing messages:
- BotName: populated from msg.BotProfile.Name for bot messages (e.g., 'giphy')
- FileCount: count of attached files
- HasMedia: true if message has files OR image blocks
This provides visibility into message types that was previously stripped
from the Slack API response, addressing user requests in issue #88.
For SearchMessage results, only HasMedia is populated (via blocks) since
the search API doesn't return BotProfile or Files data.
Generalizes error messages since this parser is now shared between
reactions_add and reactions_remove. Both tools use the same guardrail
(SLACK_MCP_ADD_MESSAGE_TOOL env var).
Companion to reactions_add (merged in #141). Allows removing emoji
reactions from messages using the same channel/timestamp/emoji params.
Tested with xoxb, xoxc/xoxd token types.
Paymahn Moghadasian