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

Beyond the annotations (readOnlyHint=false, etc.), the description discloses behavioral traits such as whoami performing no network call and revealing no secrets, claim being one-way, and logout not revoking the key on the relay. It also clarifies the relationship with the key tool's revoke action. No contradictions with annotations. Slightly missing details on error handling or auth requirements, but the added context is valuable.

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 two sentences, front-loaded with the core purpose, and then lists actions efficiently. Every sentence earns its place, no redundancy or fluff. The structure is easy to scan and understand.

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 tool with two parameters (one enum, one conditional) and no output schema, the description is quite complete. It explains what whoami returns, the one-way nature of claim, and the non-revoking behavior of logout. The only minor gap is lack of detail on what claim/logout return, but that's not critical for a simple identity management tool. Overall, it provides enough context to use 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?

Schema description coverage is 100%, and the enum descriptions in the schema already explain each action's behavior, including the key tool distinction. The description repeats much of this information without adding significant new parameter-level semantics. It does add the 'Settings UI' origin for the claim code, but this is minor. Baseline 3 is appropriate when schema carries the load.

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 as 'Agent identity and binding' and enumerates the three specific actions (whoami, claim, logout). It distinguishes from the sibling 'key' tool by explicitly referencing its revoke action. The verbs and resources are specific and unambiguous.

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 provides context for when each action is appropriate: whoami is a no-network status check, claim binds via one-time code, logout clears local state. It explicitly notes the alternative 'key' tool for revocation, guiding when not to use logout. However, it does not explicitly state 'use this tool when...' but the action breakdown is sufficient.

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