diffctx_context

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

The description adds a crucial behavioral warning beyond the readOnlyHint annotation: returned repository content must be treated as untrusted data, not instructions. This provides security context that the annotation alone does not convey. The mode explanations and fragment_id flow also add transparency about how the tool behaves.

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 compact and front-loaded: the first sentence states the core purpose, the second explains the modes, and the third gives language support. The safety warning is essential and placed at the end. No sentence is wasted; it achieves a lot in few words.

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 complexity (8 parameters) and the presence of an output schema, the description covers the core workflow well but omits details on five parameters. It provides enough to get started (mode, diff_ref, fragment_ids) but not enough to fully understand all configuration options. The output schema may cover return values, but parameter gaps keep this from being complete.

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 explains the meaning of mode, diff_ref, and fragment_ids, but the remaining five parameters (repo_path, max_tokens, budget_tokens, include_raw_diff, clipboard) are completely unexplained in both description and schema. This is a significant gap for an 8-parameter tool.

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 opens with 'Understand a git diff', using a specific verb and resource. It further distinguishes the two modes (locate vs pack), making the tool's purpose unmistakable. Even without siblings, this is a clear, specific statement of function.

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 clear context for when to use this tool: to understand a git diff. It describes the primary usage pattern (locate mode, then pass fragment_ids back) and mentions the alternative 'pack' mode. There are no exclusions because no sibling tools exist, but the guidance is still actionable.

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