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

The annotations already declare that this is a non-read-only, non-idempotent, non-destructive mutation. The description adds useful behavioral detail: omitted fields retain their values, so it is a partial update rather than a full replacement. However, it does not mention permissions, whether name changes can collide, or other side effects, so it adds only moderate value beyond 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 sentences and is front-loaded with the action and resource. The second sentence adds the key partial-update rule without unnecessary repetition.

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?

The schema is rich, including nested field descriptions, size limits, and a documentation link, and annotations cover the mutation safety profile. The description adds the essential partial-update semantics. It does not explain return behavior, but no output schema exists, so this is a minor gap rather than a blocking omission.

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 both the id and nested data fields are already documented in the schema. The description does not add field-level meaning beyond the schema; its main contribution is the general partial-update rule. A baseline 3 is appropriate when the schema carries the parameter documentation.

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 a specific verb and resource: update a knowledge document. It also clarifies the partial-update behavior with 'selected fields' and omitted fields retaining values. It does not explicitly distinguish the tool from siblings such as create_knowledge_document or set_assistant_knowledge, so it stops short of a 5.

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 implies when to use the tool by describing partial updates, but it does not explicitly say when to choose it over alternatives such as create_knowledge_document, get_knowledge_document, or delete_knowledge_document. The usage context is inferable but not spelled out.

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