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

Annotations supply only destructiveHint=true, so the description carries most of the burden and does add real value: the PATCH endpoint, the exact request body shape, and the semantics that only supplied attributes/relationships change while others are left untouched. It still omits permission/revision or validation-failure behavior, which a mutation tool ideally discloses.

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 tight sentences: the operation first, then the endpoint, then the body contract. Nothing is wasted and the most decision-relevant information is front-loaded.

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 five-parameter mutation tool with no output schema and minimal annotations, the description covers the endpoint and payload contract adequately. The remaining gap is failure-mode and permission behavior, which is minor given the body contract is fully spelled out.

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 meaning beyond the schema by showing how uuid/bundle/entity_type compose the URL and how attributes and relationships nest inside the { data: { type, id, attributes?, relationships? } } body.

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?

States a specific verb (update), resource (existing resource identified by UUID), and scope (partial update of attributes and/or relationships). This naturally separates it from the create/delete/get/list siblings without opening their schemas.

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 partial-update qualifier implies when this is preferred over a full replace, and the UUID requirement implies the caller must already know the entity. However, it never names an alternative tool or states an explicit when-not condition, so routing guidance is only implied.

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