list_capabilities

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states it returns capabilities based on session hints, which suggests a read-only operation, but provides no detail about side effects, session dependencies, error cases, or how hints affect the result. It adds some behavioral context beyond the name but lacks depth.

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 a single concise sentence that front-loads the verb and resource. It is appropriately sized for a zero-parameter tool, with no redundant phrases or filler. The only minor shortfall is that it could have briefly elaborated on what constitutes 'effective capabilities' without bloating the text.

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 has zero parameters, an output schema exists, and the description states the primary purpose, this is nearly complete. It doesn't explain how session hints are set or retrieved, but that is covered by sibling tools like auth_set_role_hints. The absence of usage guidance and behavioral detail is a small gap but not critical for a stateless query tool.

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?

The tool has zero parameters, so the input schema carries no burden. The description's mention of 'session hints' is the only substantive semantic content, and it clarifies the context the capabilities depend on. For a zero-parameter tool, this is adequate, though a slightly richer explanation of 'effective capabilities' would have pushed it to 5.

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 'Return effective capabilities for current session hints' clearly states a specific verb (Return) and resource (effective capabilities for current session hints), which is distinct enough from sibling tools. It could be more explicit about what 'capabilities' means, but it differentiates reasonably well from tools like auth_status or list_tool_catalog.

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 implies usage in the context of the current session hints, making it clear this is a read-oriented introspection tool for capabilities. However, it does not explicitly state when to use this versus alternatives like list_tool_catalog or can_execute_tool, nor does it mention 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.