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

The annotations declare readOnlyHint=true, covering safety. The description adds that it returns added, removed, and unchanged lines, which is basic output behavior. It does not disclose any potential limitations (e.g., large input handling, format details) or other behavioral nuances, but given annotations cover the safety profile, a score of 3 is appropriate.

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 only two sentences, with the action verb first, followed by use cases and output summary. Every sentence provides necessary information without redundancy, making it highly efficient and front-loaded.

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 simple tool with two required string parameters and no output schema, the description is complete: it explains the input, the operation, and the nature of the return value. The low complexity and rich annotations mean minimal additional context is needed.

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 each parameter (original, modified) is briefly described. The description does not add additional semantic details beyond the schema, so it relies on the schema to explain parameters. Baseline 3 applies when schema does the heavy lifting.

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 'Compute a unified diff between two text strings', which uses a specific verb and resource, clearly distinguishing it from sibling tools like text formatting or encoding utilities. It also specifies the comparison scope (file versions, config changes, code revisions), making the purpose unambiguous.

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 explicitly provides use cases ('Use when comparing file versions, config changes, or code revisions'), giving clear context for when to apply the tool. It does not mention when not to use it or alternatives, so it lacks explicit exclusions, but the context is solidly provided.

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