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

No annotations are provided, so the description carries full burden. It states the tool returns the input message, which implies a read-only, non-destructive behavior, but doesn't disclose any other traits like error handling, performance characteristics, or side effects. The description is minimal and lacks behavioral context.

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 extremely concise with a single sentence that front-loads the core functionality ('Return the input message') and adds context ('for testing'). There is zero waste, and every word earns its place.

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 low complexity (1 parameter, no output schema, no annotations), the description is minimally adequate. It covers the basic purpose and testing context but lacks details on behavior, error cases, or integration with siblings. For a simple tool, it's complete enough but has clear gaps in guidance.

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%, but the description adds meaning by explaining that the 'message' parameter is returned as output. However, it doesn't elaborate on parameter constraints, format, or examples. With 1 parameter and no schema descriptions, the description provides basic semantics but could compensate more for the coverage 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 clearly states the tool's purpose with 'Return the input message' and specifies it's 'for testing', which distinguishes it from sibling tools like compress/decompress. However, it doesn't explicitly contrast with siblings beyond the testing context.

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 usage context with 'for testing', suggesting this is a diagnostic tool rather than for production workflows. It doesn't provide explicit guidance on when to use versus alternatives like compress or decompress, nor does it specify prerequisites or exclusions.

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