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

Adds substantial context beyond annotations: it creates the account and apartment (mutation), returns a Stripe payment URL, is free until the month ends, and never exposes card details to the agent. It also explains the idempotent-equivalent behavior despite annotations already hinting at it.

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?

Front-loads the precondition and outcome, then layers detail. Slightly dense with parenthetical asides, but no sentence is wasted.

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 2-parameter mutation tool with no output schema, the description covers preconditions, return value, security posture, idempotency, and next steps, leaving nothing material for the agent to infer.

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 100%, so the baseline is 3, but the description adds the workflow context that setup_id and status_token come from create_setup and that the token must stay private, which reinforces the schema's privacy note.

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 outcome: creates the account and apartment and returns payment_url. It distinguishes itself from siblings by naming the precondition (after confirm_phone_code) and the output artifact, so an agent can identify it without opening the 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?

Explicitly sequences the call after confirm_phone_code and explains what to do with the result (give the link to the person or use message_for_the_person). It also covers the re-call case: calling it again returns a fresh link for the same apartment.

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