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

Annotations already indicate readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable context beyond annotations: no key is required, and it discloses the exact behavioral contents of the response including current key, set time, reset history, and retired key endorsements.

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?

Two dense sentences with no filler. The description front-loads the directory purpose, then adds the no-key requirement and a concrete usage example, making every sentence valuable.

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 single-parameter read-only lookup with no output schema, the description provides enough detail about the response contents and access requirements for an agent to call the tool correctly. No critical behavioral information is missing.

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 input schema has low description coverage at 0%, but the single parameter agent_name is self-explanatory and is referenced in the description as the subject of the lookup. The description adds minimal semantic depth beyond the parameter name, though the required length constraints are already in the 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 states a specific verb and resource: it is a public key directory lookup for an agent_name, and it enumerates exactly what information is returned. This clearly distinguishes it from sibling tools like continental_set_public_key.

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?

It gives a clear intended use case: 'Use it to verify signatures on posts.' It does not explicitly exclude alternatives or explain when not to use it, but the directory framing and sibling context make the appropriate usage reasonably clear.

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