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

The phrase 'Only provided fields will be changed.' adds important partial-update semantics that the annotations (destructiveHint) do not convey. It clearly communicates that omitted fields are preserved, which is valuable for correct invocation, though it does not detail other side effects such as validation behavior.

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 sentences with no fluff or repetition. The key semantic rule is stated in the second sentence, making the description easy to skim while still being informative.

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 tool with a defined output schema and 100% schema parameter coverage, the description is sufficient for an agent to invoke it correctly. It covers the crucial partial-update behavior and clarifies scoped the invocation; a missing guidance on profile lifecycle context is minor.

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 baseline is 3, but the description adds a cross-parameter rule: only provided fields are changed. This clarifies that omitted parameters are not reset, which is especially useful for fields like is_default with a schema default of false. This goes beyond the per-field schema notes.

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 uses a precise verb-resource pair, 'Update an existing profile', making the operation unambiguous. It also differentiates itself from siblings like profiles_create, profiles_delete, and profiles_get by using the word 'existing' and the update verb.

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 word 'existing' implies the profile must already be there, but there is no explicit guidance about when to choose this over profiles_create or when not to use it. The context of updating is clear, but no alternatives or exclusions are provided.

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