Rules that do not do what they look like

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

With no annotations, the description carries the full burden. It details multiple behavioral aspects of the tool: it surfaces rules that are ignored, misanchored, over-broad, or shadowed, and each finding includes documented behavior. It does not explicitly state that it is read-only, but the analytical nature is evident. This is above minimum but could say more about outputs.

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 three sentences and packed with useful detail, but the first sentence is quite long and lists many edge cases. It is still concise and every part contributes to understanding the tool's purpose, though a more front-loaded verb would improve scannability.

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 no output schema, so the description should clarify what the results look like. It only says 'Each finding cites the documented behaviour,' which gives a hint but not the complete shape of the output. Given the tool's diagnostic nature and the rich input schema, the description is adequate but leaves room for more detail.

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?

The input schema already has full descriptions for both 'dir' (absolute path, default working directory) and 'kind' (enum with five categories). The description does not add any additional parameter-specific details, so it relies entirely on the schema. Baseline of 3 applies since schema coverage is 100%.

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 clearly defines the tool's scope: it identifies permission rules whose documented behavior differs from their apparent intent. It enumerates specific categories (inert, misreads, wider, shadowed) which makes the purpose concrete, but it lacks an explicit verb like 'find' or 'list,' so it's slightly less direct than 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 final sentence gives concrete guidance: 'Use before trusting a guard rail you wrote a while ago.' This indicates when to use the tool, but it does not explicitly mention alternative sibling tools or when not to use it. Still, the context is clear and actionable.

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