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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description reinforces these traits and adds valuable behavioral context: error handling behavior ('never raises a protocol error — it returns an error object'), and the safety of retrying after correcting input. This goes beyond the 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 well-structured with front-loaded purpose, clear sections, and no wasted words. It is slightly longer than necessary due to the example and error handling details, but every sentence adds value. A minor trim could improve conciseness.

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?

Given the tool's simplicity (1 parameter, good annotations, output schema exists), the description covers all essential aspects: purpose, input format, output structure (mentioning keys), error behavior, and usage guidelines. No gaps are evident.

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?

Although schema coverage is 100% for the single parameter, the description adds significant meaning: it lists multiple accepted input formats (JSON array, object, newline-separated) and provides a concrete example. This helps the agent construct valid input far beyond the schema's minimal description.

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+resource: 'Score the blast radius of every tool in a permission manifest.' It clearly states the tool's purpose and distinguishes it from the sibling 'audit_mcp_config' by explicitly saying 'Not for the configuration that mounts them.'

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 tells when to use the tool ('Use on a permission manifest to rank tools by blast radius') and when not to use it ('Not for the configuration that mounts them (audit_mcp_config)'). This provides clear guidance for an agent to select the correct tool among siblings.

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