Update a mailbox password

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

Annotations already convey readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description adds meaningful behavioral context beyond these: the password is 'written straight through to the provider and never recorded here,' and the operation returns the updated subscription. This discloses data-handling behavior that the annotations do not cover.

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 with no filler. The primary action is front-loaded, followed by return behavior and a valuable note about data handling. The reference to the sibling tool is concise and earned.

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?

Given the rich input schema with 100% coverage, an output schema, and annotations covering safety/idempotence, the description supplies the remaining essential context: what the operation does, what it returns, and how to find the target subscription. An agent has enough information to invoke it correctly without missing dependencies.

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%, with both 'id' and 'body' fully documented in the input schema, including the nested password fields. The description adds little beyond what the schema already states, which is acceptable given the schema carries the semantic load. 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?

The description names a specific verb, resource, and outcome: 'Sets a new password on the mailbox of an email subscription and returns the updated subscription.' This clearly distinguishes it from sibling email tools like set_alias and set_catchall, and the reference to get_subscription further orients the agent.

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 tells the agent how to locate the target entity by instructing to 'find the subscription with eurodns_email_get_subscription,' which provides a clear prerequisite. It does not explicitly list when-not-to-use or contrast with alternative email mutation tools, but the purpose is specific enough that an agent can infer the correct selection context.

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