echo

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

With no annotations provided, the description must carry the transparency burden. It clearly discloses that the message is returned without modifications, which covers the core behavioral trait of an echo operation. It does not go into edge cases or error behavior, but none are essential for this simple tool.

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?

A single, front-loaded sentence with no filler. It conveys the entire behavior efficiently and earns every word.

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 with an output schema present, the description is nearly complete: it identifies input, behavior, and result. It lacks explicit usage guidance, but the simplicity of the tool lowers the burden, so only a minor gap remains.

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 0%, so the description must compensate. It does by linking the single 'message' parameter to the returned value, clarifying that the parameter is the exact input echoed back. This adds semantic meaning beyond the bare schema property name and type.

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 specific verb ('Devuelve') and resource ('el mismo mensaje recibido'), making the tool's identity operation unmistakable. It also naturally distinguishes itself from siblings like 'reverse' and 'add' by emphasizing that no modification occurs.

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?

The description implies the appropriate use case: invoke this tool when the exact original message must be returned unchanged. However, it does not explicitly mention alternatives or state when not to use this tool, leaving the guidance implicit rather than direct.

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