list_roles

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

Annotations only provide readOnlyHint, and the description adds meaningful behavioral context beyond that: it explains the two possible 'source' values, which is authoritative, and the under-reporting caveat in stdio mode. This gives the agent a realistic expectation of reliability.

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 compact and front-loaded with the core purpose, then adds only the necessary caveat about source behavior. Every sentence earns its place without wasted words.

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?

For a zero-parameter read-only tool with an output schema, the description covers the essential behavior, the two runtime modes, and the key limitation. Nothing critical is missing for an agent to invoke and interpret it correctly.

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?

There are zero parameters, so the schema already leaves nothing ambiguous. The description still clarifies what the tool returns, but no parameter documentation is needed.

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 answers a clear user question ('Who is in this channel') and states the exact return shape ({roles, you, source}). It distinguishes list_roles from siblings like list_channels and add_role by targeting channel membership specifically.

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 explains when the data is authoritative (hosted mode with channel registry) versus inferred (stdio mode) and warns about under-reporting. However, it does not explicitly say when to choose list_roles over alternatives or when not to use it.

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