echo

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

With no annotations provided, the description carries the full burden. 'Echo back' implies a side-effect-free, idempotent read, which is the key behavioral trait, but it never states this explicitly, nor does it describe the return value or any limits beyond the schema's maxLength. Adequate but not rich.

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 short sentences with zero waste; the core action is front-loaded and the second sentence adds useful framing. Nothing is padded.

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 trivial one-parameter tool whose schema fully documents the input, this is nearly complete. The only minor gap is that, absent an output schema, the description never states that the return value is the same message echoed back.

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 description coverage is 100% and the single 'message' parameter is documented as 'Text to echo back', so the schema does the heavy lifting. The description adds only the informal hint that the message is 'short', aligning loosely with the 500-char cap, so it stays at the baseline.

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+resource: 'Echo back a short message.' An agent immediately understands the operation, and there are no siblings to distinguish it from. Slightly loses a point only because 'short message' is informal where a precise scope would be better.

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?

'Useful as a hello-world MCP tool' gives implied usage context — it signals this is a demo/smoke-test tool rather than a production operation. However, it does not state when an agent should prefer this over any other action, nor any exclusions, so the guidance remains implied rather than explicit.

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