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

With no annotations provided, the description carries the full burden and does a solid job: it states the mutation intent, the partial-update semantics ('Omitted fields are left unchanged (not cleared)'), and the authorization requirement. It leaves some behavior unspecified, such as what explicit null values do versus omitted fields and what the response contains, but the disclosed traits are the most important ones.

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 concise sentences, with the action and target front-loaded and the key partial-update and auth caveats right after. No filler, no repetition of schema content.

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 simple 4-parameter update tool with full schema coverage, the description covers the core information an agent needs: what to update, partial-update behavior, and the required credential context. It does not mention response format or error cases, but it is otherwise complete enough to invoke the tool correctly.

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. The description adds the 'not cleared' nuance, but it does not clarify the meaning of explicit nulls, which are allowed in the schema for name and scope_expressions, or otherwise expand on the parameter-level details already present.

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 specific verb ('Update') and identifies the exact resource (a role) along with the mutable fields ('name and/or scope_expressions'). It clearly distinguishes this tool from create_role, delete_role, and other role-related siblings based on action alone.

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: use this when updating an existing role's name or scope expressions, and it notes the admin owner_key requirement. It does not explicitly contrast against alternatives like create_role or delete_role, but no exclusion guidance is needed for obvious sibling differentiation.

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