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

With readOnlyHint=true already covering safety, the description still adds substantial behavioral context: values are never echoed (privacy/secret handling), input failing schema is rejected before billing, and each successful call costs 2 credits. These are non-obvious traits an agent cannot get from 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?

Four tightly written sentences, no filler: purpose first, return shape second, privacy guarantee third, billing fourth. Every sentence carries information the agent needs.

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 single-parameter validator with no output schema, the description fully compensates by describing the return shape ({ ok, servers, findings, counts }), privacy guarantees, and billing behavior. Nothing needed to invoke it correctly 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?

There is a single parameter with 100% schema coverage, so the schema already explains the JSON-string-or-object form and the 60,000-character limit. The description adds no further parameter semantics, making the baseline 3 appropriate.

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 names a specific verb and resource — 'Validates a Claude Code .mcp.json' — and enumerates the facets it checks (transports, commands, URLs, headers, env, literal secrets by path). This clearly separates it from generic siblings like json-validate or tool-schema.

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?

Usage is implied by the 'Claude Code .mcp.json' scoping, but there is no explicit when-to-use/when-not guidance and no named alternative (e.g. json-validate for generic JSON). An agent can infer the context but must reason about it.

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