diff

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

With no annotations, the description carries the full burden. It discloses the operational behaviors for every mode without hiding assumptions or side effects. There is no mention of side effects or permissions, but for a read-only diff operation, the behavior is transparent enough.

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?

Two sentences, front-loaded with the core purpose, followed by a precise enumeration of modes. No wasted words or redundancy.

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?

The description covers all parameter combinations and default behavior, and with no output schema, return details are not required. It is slightly thin on the definition of 'structural drift' and possible error conditions, but overall it gives a complete mental model for using the tool.

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 coverage is 100%, but the description adds meaningful semantic grouping: it explains that a and b are used together, `since` uses a label against live code, and `session` pins the reference snapshot. This goes beyond the schema's literal parameter descriptions.

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 'Structural drift for an enrolled repo' and enumerates three distinct comparison modes (snapshot-snapshot, snapshot-live, latest snapshot-live). This signals a specific verb+resource and differentiates it from sibling tools like 'structure' or 'status'.

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 provides explicit usage context by defining when each mode applies: with a+b for snapshot diffs, with `since` for snapshot-vs-live, and default for latest-vs-live. It doesn't name alternative tools, but the decision logic is clear and tied to argument combinations.

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