emacs_ediff_regions

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states a read-only comparison action, but does not explicitly confirm that no state is modified, nor does it explain the shape of the returned diff, error behavior, or whether the operation is a true ediff invocation. The description is minimal and leaves these behavioral traits undisclosed.

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 a single focused sentence with no filler or repetition. It states the action, the resource, and the output in six words, which is appropriately concise and front-loaded.

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 parameter schema is complete and the core purpose is sufficiently clear for invocation. However, there is no output schema and no mention of what the returned diff looks like, how format interacts with the output, or when this tool should be preferred over sibling diff tools. It is minimally adequate but leaves notable gaps.

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%, so all six parameters are already documented in the input schema. The description adds no parameter-specific meaning, but the schema carries the semantic weight, 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?

The description uses a specific verb ('compare') and resource ('two text regions') and states the result ('return the diff'). It clearly distinguishes from sibling tools that operate on files or buffers, though it does not name them explicitly.

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?

There is no guidance on when to use this tool versus emacs_ediff_files, emacs_ediff_buffers, emacs_ediff_3way, or emacs_diff_summary. No alternatives or exclusion conditions are mentioned, so the agent must infer appropriate usage from the name and description alone.

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