Slack MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions the tool fetches message history but doesn't cover important aspects like rate limits, authentication requirements, pagination behavior, error conditions, or whether this is a read-only operation (though 'fetch' implies reading). Significant behavioral details are missing.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured and efficiently organized with clear sections for purpose, arguments, and returns. Every sentence serves a specific purpose with no wasted words. The information is front-loaded with the core purpose stated first.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's moderate complexity (4 parameters, 1 required), no annotations, but with an output schema (returns dictionary with message list), the description is mostly complete. It thoroughly documents parameters and purpose, though could benefit from more behavioral context about limitations, permissions, or error handling to be fully comprehensive.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0% schema description coverage, the description fully compensates by providing detailed parameter documentation. It explains each parameter's purpose, provides examples (e.g., 'D01234567'), specifies valid ranges (1-1000 for limit), indicates optionality, and documents default values. This adds substantial value beyond the bare schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose with specific verbs ('fetch message history') and resources ('DM or group DM conversation'), distinguishing it from siblings like get_channel_history (for channels) and get_thread_replies (for threads). It precisely identifies the scope of the operation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implicitly suggests usage for retrieving DM conversation history, but lacks explicit guidance on when to use this tool versus alternatives like get_channel_history or get_thread_replies. It provides context (DM conversations) but no explicit exclusions or comparisons with sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.