Update Mail User

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

Annotations already declare readOnly=false, idempotent=true, destructive=false, and openWorld=true. The description adds a concrete non-obvious behavior: it flushes the MCP cache. It still omits permissions and update scope details, but the added side effect is valuable beyond the annotations.

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?

The description is two short labeled lines with no filler. Purpose and side effects are front-loaded and easy to scan.

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 mutation with a nested, dynamically typed settings object and no output schema, the description covers the endpoint and one important side effect. It does not explain what settings can contain, permissions, or update scope, leaving some contextual gaps despite strong schema and annotation support.

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 domain, key, and settings documented in the schema. The description's path placeholders do not add meaning beyond the schema, so the baseline of 3 applies.

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 states the exact REST operation and path, `PUT /v1/domains/{domain}/users/{key}`, which identifies both the resource and the mutation. It distinguishes this tool from sibling user operations by method and path, though it does not spell out 'update mail user settings' in prose.

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?

There is no when-to-use guidance, no comparison to siblings such as users.create, users.get, or users.delete, and no prerequisites. The agent can infer usage from the endpoint, but the description provides no explicit usage guidance.

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