Rename a contact group

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

Annotations already indicate this is a mutation (readOnlyHint=false, destructiveHint=true). The description adds valuable behavioral detail: etag-based concurrency handling with auto-fetch fallback, rejection of system groups, and uniqueness enforcement causing 409. It also states the return value. No contradiction with 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?

Three dense sentences: the first states the core action and scope, the second explains etag behavior, the third covers limitations and the result. No redundant phrases; all sentences carry essential information. Front-loaded with the primary purpose.

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 concurrency, system-group restrictions, and uniqueness constraints, the description covers all critical aspects: behavior, edtag options, failure modes (409), and return value. No output schema exists, but the return is stated. Minor gaps like other error codes (e.g., 404) are acceptable given the specificity.

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 covers all 3 parameters with descriptions, including the etag 'omit to auto-fetch' note. The description repeats this etag guidance but adds no new parametric meaning. Since schema coverage is 100%, the baseline of 3 is appropriate; the description does not compensate beyond schema.

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 opens with a specific verb and resource: 'Renames a user contact group'. It also states the scope ('the only mutable group attribute'), which clearly distinguishes it from create/delete/modify operations. While no sibling is named, the uniqueness of the action is unambiguous.

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 provides clear context on when to use the tool: it's for renaming, and it explicitly warns that system groups cannot be renamed, implying alternative handling. It also explains the etag strategy (pass to avoid concurrent overwrites, omit for auto-fetch) and uniqueness constraint. It does not explicitly contrast with create/delete tools, but the purpose is obvious.

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