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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds no behavioral context beyond 'Fetch,' such as pagination via cursor, max_characters chunking, or version/section selection behavior. Given that these behaviors are meaningful and undisclosed, the description falls short.

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 a single, front-loaded sentence with no wasted words. 'Fetch Locus guides' identifies the action and object immediately, and the condition adds necessary usage context.

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 tool has six optional parameters and an output schema, but the description gives no high-level orientation (e.g., how to list vs. fetch a specific guide, pagination behavior). The schema covers individual parameters, so the description is minimally adequate, but it leaves the agent to infer the overall usage pattern from schema fields alone.

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 itself provides no parameter-level detail, but the schema already documents id, task, cursor, section, version, and max_characters, so the description does not need to compensate.

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 ('Fetch Locus guides') and provides a scoping condition ('when native skills are unavailable'). It is clear about what the tool does, though it does not explicitly name sibling tools, leaving the differentiation to the 'native skills' phrase.

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 gives an explicit when-to-use condition: 'when native skills are unavailable.' This is a clear contextual trigger, but it does not mention any sibling tools by name or provide explicit when-not-to-use guidance beyond the implied condition.

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