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

Annotations only declare the safety profile (not read-only, not destructive, not idempotent, closed-world). The description adds real behavioral context beyond that: the recipient signs in with an emailed code, may add a card or continue without one, and the tool returns both a link and a token. It does not mention auth requirements or rate limits, but the async handoff flow is well disclosed.

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 sentences, front-loaded with the outcome and followed by the next-step instruction. Dense but every clause carries information; the polling detail and return format are both relevant rather than 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?

With no output schema, the description carries the burden of explaining returns and does so: this tool yields a link and token, and check_setup_link yields one API key per site plus an optional server key. Combined with a fully documented input schema, this is nearly complete, though a note on link expiry or failure handling is absent.

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%, so the schema already documents email, domains, and serverKey thoroughly. The description echoes the site-to-key mapping and the server-key option ('a server key if you asked'), adding only marginal meaning over the schema. Baseline 3 is appropriate.

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 (gets/creates) and resource (TraceTail API keys via a setup link) and names the exact sibling to call next. An agent can distinguish this from check_setup_link and the docs/pricing siblings without opening a 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 description gives clear workflow context: use this to obtain keys for 'the person you work for,' then 'call check_setup_link with its id and token every few seconds.' It names the follow-up tool and the polling cadence, but offers no explicit exclusions or when-not-to-use guidance, so it falls short of a full 5.

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