diff

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

No annotations are provided, so the description must carry behavioral disclosure. It explicitly states 'Read-only' and describes the output (summaries, status lines, git refs) and default behavior (previous vs latest checkpoint). It does not discuss permissions or rate limits, but for a read-only diff, the key behavior is covered.

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 concise: four sentences with no unnecessary words. It front-loads the main action and output, then covers defaults, use case, and safety. Every sentence earns its place without 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?

Given the simplicity of the tool (no output schema, two optional params), the description fully explains what to expect: content (summaries, status lines, git refs), default comparison points, the use case, and the read-only nature. No missing information for an agent to invoke it correctly.

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%, so baseline is 3. The description adds value by explaining the defaults: 'to' defaults to the latest checkpoint, 'from' defaults to the second-most-recent. This clarifies the comparison direction beyond the schema 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 the tool's action (compare), resource (two checkpoints), and output (summaries, status lines, git refs). It is distinct from sibling tools, none of which perform comparison. The phrase 'Call to see what changed between sessions' further reinforces the purpose.

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 an explicit use case ('see what changed between sessions') and implies when to call it. However, it does not mention when not to use it or alternative tools. Given that no sibling tool does a similar comparison, this guidance is sufficient.

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