session_diff

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

The description adds significant behavioral context beyond readOnlyHint: the first call records a baseline, subsequent calls return diffs, track IDs are scoped to the bridge, and older bridges cannot reliably detect renames. This is crucial stateful behavior that annotations alone would not convey.

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 dense but efficient: the first sentence covers scope, the second covers caveats about baseline and bridge scoping, and the third provides usage guidance. Every sentence adds necessary information 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?

For a parameterless tool with an output schema and readOnlyHint, this description is complete. It explains the tool's stateful nature, the baseline behavior, the reliability limitation, and the recommended call pattern. Nothing essential 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?

The tool has zero parameters and the input schema is empty, so there is no parameter ambiguity. The description focuses on behavior rather than parameters, which is appropriate and meets the baseline for a parameterless 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 clearly identifies the tool as a diff/reporting tool for session changes, enumerating the specific elements it tracks. However, it does not explicitly distinguish itself from similar sibling tools like als_diff or get_session_snapshot, so it lacks direct sibling differentiation.

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 an explicit usage pattern: call it before and after an edit to verify the change took effect. It does not mention alternatives or exclusion criteria, but the context is clear enough for an agent to know when it applies.

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