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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds a useful behavioral trait: an unknown id is not a dead end, and the answer provides near-miss ids to retry. This exceeds what annotations convey.

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 sentences, front-loaded with the action, followed by a clear usage condition and a helpful edge-case note. No waste; every clause earns its place.

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 description tells the agent what the tool returns, when to call it, and how to recover from an unknown id. The output schema covers the return shape, so nothing critical is missing for a one-parameter read-only tool.

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 coverage is 100%, and the schema already explains the id parameter including how to obtain it and the canonical URL hint. The description merely says 'by id' and adds an error-recovery note for unknown ids, which adds little semantic detail beyond the 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: 'Fetch one knowledge object by id', and names the payload ('with its claims and the sources each claim cites'). It also implicitly distinguishes from siblings by noting when it applies ('Use this once search, answer or get_topic has given you an id'), making it clear this is the targeted retrieval step.

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 explicitly states when to use the tool: 'Use this once search, answer or get_topic has given you an id.' It gives clear context, though it doesn't explicitly list when not to use it or name a sibling alternative.

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