functions_complete_error
Signal that a function failed to complete.
This record as markdown: /tools/karbassi-slack-mcp/functions-complete-error.md
What functions_complete_error does on Slack
AI agents use functions_complete_error to create or update resources in Slack, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Slack environment.
Why functions_complete_error is rated Medium
This tool modifies state by marking a function as failed (vs. completed), which is a reversible write operation that updates metadata/records in Slack. While not directly creating/modifying message content or user data, it performs an irreversible business logic state transition.
From the tool's definition Tool description states 'Signal that a function failed' - this writes an error status/state change to Slack's function execution system, creating or modifying record of a function's completion status.
Attacks that exploit this kind of access
The rule that runs functions_complete_error safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Slack, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For functions_complete_error, this is the rule to start with:
functions_complete_error stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Slack, apply this rule, and every functions_complete_error call is checked against it from then on.
Questions about functions_complete_error
Signal that a function failed to complete. It is categorised as a Write tool in the Slack MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Slack MCP server in PolicyLayer and add a rule for functions_complete_error: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Slack. Nothing to install.
functions_complete_error is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the functions_complete_error rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for functions_complete_error. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
functions_complete_error is provided by the Slack MCP server (karbassi/slack-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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