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

Beyond readOnlyHint=true and openWorldHint=false, the description discloses that credentials are redacted and that 'nothing is posted or stored' — meaningful behavioral context the annotations don't convey. It does not describe the exact response shape or size limits, keeping it below 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?

Two tight sentences; the return contract is front-loaded and the guarantee about redaction/no storage follows immediately. Nothing is repeated or wasted.

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 diagnostic tool with no output schema, telling the agent what comes back (arguments, redacted headers, connection details) and that nothing is stored is nearly sufficient. Only minor detail on the response format is absent.

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 0% and the single 'message' parameter is undocumented. However, the description's 'your arguments' phrasing, combined with additionalProperties=true, implies arbitrary arguments are accepted and echoed, which partially compensates for the gap.

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 states a concrete verb and result — 'Return exactly what the server received' — and enumerates what that includes (arguments, redacted headers, connection details). No sibling differentiation is given, though the siblings (notes, messages, swarm keys) are unrelated and not easily confused with echo.

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?

'For testing MCP clients' gives a clear condition for use and implicitly rules out production/data use. It stops short of naming alternatives or explicit when-not-to-use cases, but for a diagnostic tool that is a reasonable scope statement.

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