fable_file_diff

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

No annotations are provided, so the description carries full burden. It mentions 'unified diff' which implies a standard output format, but does not explicitly state that the operation is read-only, nor does it disclose any potential side effects. The description is adequate but could be more explicit about behavior.

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 two sentences long, front-loaded with the primary purpose, and contains no superfluous information. Every sentence is essential and clear.

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 diff tool with three parameters and no output schema, the description is largely complete. It specifies inputs (path, version indices) and output format (unified diff), and references the companion tool for obtaining indices. It could briefly describe the output format, but 'unified diff' is sufficiently standard.

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?

The schema covers 2 of 3 parameters with descriptions (a and b). The description adds context by linking the version indices to the sibling tool fable_file_history, but does not elaborate on the 'path' parameter beyond what is obvious. This adds moderate value beyond the schema.

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 explicitly states the tool computes a 'unified diff between any two reconstructed versions of a file', using a specific verb and resource. It references version indices from a sibling tool (fable_file_history), clearly distinguishing it from other file-related tools like fable_file_history or fable_files.

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 gives concrete usage scenarios: 'recover exactly what changed between two past edits, or between a past version and the latest'. It also instructs to pass 'the file path and the two version indices a and b'. While it does not explicitly exclude alternatives, the context makes it clear when to use this tool.

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