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

Goes well beyond the annotations: it discloses the returned client_session and its 30-minute validity, the five-tries-per-code rate limit, and what to do on failure. It leaves out what happens once the five attempts are exhausted (lockout? new challenge required?), which is the one behavior an agent most needs to avoid trapping a client.

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?

Three short sentences, front-loaded with the action, then the success payload, then the constraint and recovery path. No filler.

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?

Covers the return value, expiry, retry limit, and failure recovery, which is most of what an agent needs for a two-parameter verification tool with no output schema. The unexplained challenge_id and the undefined post-limit state keep it from being complete.

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 coverage is 0%, so the description carries the burden. It clarifies that 'code' is the 6-digit code from the client's email, but challenge_id, a required parameter, is never mentioned or linked to a prior start_client_sign_in call.

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?

States a specific verb and resource ('Checks the 6 digit code from the client's email') and makes the scope clear enough that an agent can separate it from start_client_sign_in without opening either schema.

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 failure path explicitly routes the agent: ask the client to check the newest email, or restart with start_client_sign_in. It does not explicitly state that this must be called after start_client_sign_in with the challenge_id that call returned, which is the main missing piece of routing guidance.

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