uvcs_diff_file

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description's own 'Read-only' merely repeats structured data. It does add one genuine behavioral fact not in the annotations — truncation above 200000 characters — but omits any error or permission behavior for a pending-file diff.

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?

Three compact sentences, front-loaded with the core comparison and followed by the truncation caveat. The only waste is the trailing 'Read-only', which duplicates the annotation; otherwise every sentence carries information.

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 read-only diff tool with no output schema, the description identifies the two versions being compared and the truncation limit, which is enough to call it correctly. It could mention output format (unified diff text) more explicitly, but nothing critical is missing.

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%: both filePath (path relative to UVCS_WORKSPACE of a file with a pending change) and context (0-20 unchanged lines, default 3) are fully documented in the schema. The description adds no parameter detail beyond what the schema already conveys, so the baseline of 3 applies.

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 (return a unified line diff) and resource (one pending file), and defines scope precisely as the workspace revision versus the file on disk. It does not name the sibling diff tools (uvcs_changeset_diff, uvcs_revision_diff), so an agent must infer the distinction from the scope wording rather than being explicitly routed.

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 phrase 'one pending file' implies usage and the comparison pair tells the agent what this diff covers, but no when/when-not or named alternatives are provided. With near-identical siblings like uvcs_revision_diff and uvcs_changeset_diff present, guidance on when to prefer this tool is implied rather than stated.

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