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

The description goes well beyond the annotations: it discloses that the tool makes 5 network requests, waits 6 seconds each, reports HTTP status and JSON-RPC error codes side by side, flags HTML/5xx responses where JSON-RPC errors belong, and supports a fixture that fails two checks. This adds meaningful behavioral context beyond readOnlyHint, idempotentHint, and openWorldHint, and does not contradict them.

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 dense but efficient; every sentence carries useful operational information and it is front-loaded with the essential first-call payload. However, the long parenthetical list of five test cases with expected codes makes it a wall of text that could be parsed more easily with separate lines or clearer separation.

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 moderate complexity and the absence of an output schema, the description is remarkably complete: it covers inputs, the exact requests sent, expected JSON-RPC error codes, output behavior (HTTP status vs error code), the HTML/5xx failure condition, request count, timeout, and fixture behavior. An agent can confidently invoke and interpret this tool from the description 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?

The schema already describes the url parameter fully (100% coverage). The description adds extra value with a concrete example URL and the {} fixture alias with expected failure behavior, which helps an agent select the right input without opening the schema. Slightly more detail on URL edge cases exists in the schema, so this is strong but not a 5.

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 states a specific verb and resource: it is an error-conformance linter that sends five deliberately malformed JSON-RPC requests to an MCP endpoint and checks the returned HTTP status and JSON-RPC error codes. This makes it distinguishable from siblings like handshake_report or discovery_report, which target different aspects of endpoint behavior.

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 clearly conveyed: it explains what to send, the expected error codes for each probe, that it makes 5 requests with 6-second timeout each, and how to choose between an external URL and the fixture via {}. It does not explicitly name when to prefer this tool over sibling alternatives, but the operational context is strong enough to avoid confusion.

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