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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds value by specifying the returned statistics (size by provenance, last changed), but it does not describe response format, pagination, or any operational constraints. With annotations carrying the behavioral load, this is an adequate but not rich disclosure.

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 fragment with no wasted words, and it front-loads the core output content. It could be slightly clearer with an action verb, but it is efficiently sized for a no-param tool.

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 no parameters and no output schema, the description should ideally explain the shape of the returned statistics. It does provide a high-level summary (size by provenance, last changed), but it leaves the exact response structure unspecified and does not clarify which index is being described, leaving a minor completeness gap.

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 baseline is 4. The schema is empty and the description does not need to explain any parameter semantics, making this dimension appropriately handled.

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 names the resource (the index) and the data dimensions (size by provenance, last changed), but it is a noun phrase without an action verb and does not differentiate itself from related siblings like mcp_index_signals or api_index. An agent can infer it is a stats endpoint, but the purpose is not sharply defined.

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?

There is no guidance on when to use this tool versus alternatives, no prerequisites, and no context about what 'the index' refers to. The description only states what data is returned, leaving the agent to infer usage.

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