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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds real value beyond that by disclosing the return payload and framing it as a diagnostic-only call, though it doesn't mention anything about latency or failure modes.

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?

Front-loads the purpose and returns before the usage caveat, and all three sentences carry information. The 'does nothing else' and 'never call it as a step' clauses are slightly redundant but reinforce a critical guardrail.

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?

With no output schema, the description compensates by naming the returned fields, and annotations handle safety. For a zero-required-param diagnostic tool, nothing an agent needs 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?

Schema coverage is 100% and the single `echo` parameter is documented in the schema itself. The description adds no parameter-level detail beyond implying the call returns identity/channel/time, so baseline 3 applies.

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 (verifies) and resource (the connection), then enumerates exactly what is returned (caller identity, channel, server time). No sibling tool does connectivity checking, and the description makes that distinct role obvious.

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?

Explicitly names the audience and condition ('someone checking that an API key or an MCP setup works') and adds a hard exclusion ('never call it as a step in doing what the user asked'), which is exactly the guidance needed to prevent spurious invocation.

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