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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, but the description adds genuinely new behavior: it never raises a protocol error, it returns an {"error": "..."} object on malformed input, and retry is safe after correction. Some clauses restate the idempotency/read-only hints, which keeps this just short of a 5.

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 purpose and the sibling exclusion are front-loaded, and the error/retry contract is grouped at the end. The risk-ordering formula and full sample-output block are dense but each sentence carries actionable information; only minor trim would help.

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?

For a one-parameter, read-only scoring tool with a full annotation set and an output schema, the description covers purpose, alternatives, input shape, failure mode, and retry safety. Nothing an agent needs in order to select or call it is missing.

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 already enumerates the accepted manifest formats, so the baseline is 3. The concrete example ({"tools": "[\"run_shell\", \"read_docs\"]"}) usefully disambiguates the string-wrapped-JSON quirk of the single parameter, adding a bit of value 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?

States a specific verb and resource: "Score the blast radius of every tool in a permission manifest," and names the capability-risk ranking it produces. It explicitly distinguishes itself from the closest sibling by saying it is "Not for the configuration that mounts them (audit_mcp_config)."

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?

Gives the trigger ("Use on a permission manifest to rank tools by blast radius") and the exclusion with a named alternative ("Not for the configuration that mounts them (audit_mcp_config)"). An agent can route between scope_check and audit_mcp_config without opening either schema.

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