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

Annotations already declare non-readOnly, non-destructive, non-idempotent, so the description adds real value by promising state preservation ('The city and everything in it stay') and the regained capabilities (real-money purchases, re-login). It doesn't disclose what happens on a second call to an already-claimed account, which is exactly the failure mode the non-idempotent hint implies.

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 core transformation, then the state-preservation guarantee, then the capability delta. No filler and no restatement of the title.

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?

An output schema exists and annotations cover the safety profile, and the description covers purpose, state effects and post-claim capabilities. The gap is error behavior for an ineligible or already-claimed guest, which matters for a non-idempotent mutation.

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% with per-field descriptions and a documented 6-character password minimum, so the schema carries parameter meaning. The description adds only the framing that these become login credentials; it says nothing extra about display_name or credential validation.

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 object ('turn this guest account into a full account') and pins it to the exact server operation (POST /v1/guest/claim), so it is distinguishable from register/login/guest_login by the guest-conversion scope. It stops short of naming a sibling tool to contrast with, so an agent must infer that this is not the same as register.

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?

Gives clear applicability: use it when a guest account should be persisted with email/password, and it notes the consequence (guests can't pay with real money, claimed accounts can). It also hints at the follow-up path ('can log in again with login'), but never states when this tool should be avoided — e.g. calling it on an already-claimed account.

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