diffci_explain_selection

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

Annotations already declare readOnlyHint=true and openWorldHint=false. The description adds useful behavioral context beyond that: it inspects staged, unstaged, and non-ignored untracked changes, returns a snapshot-bound plan and fallback reasons, runs no tests, and clarifies that a plan is not a passing receipt. It does not describe how the plan is computed or how fallback reasons are generated, so it stops short of a full behavioral account.

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 two tight sentences with no wasted wording. The core scope is front-loaded, and the second sentence adds an important boundary condition without repetition.

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 low-complexity, single-optional-parameter, read-only tool with no output schema, the description covers what is inspected, what is returned, and the key limitation that no tests are run. It is nearly complete, though the exact shape of the affected-test plan and fallback reasons remains somewhat open.

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%, and the sole optional repo parameter is fully documented in the schema. The description adds no additional meaning about the repo parameter, so the schema does the heavy lifting and the baseline score 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 states a specific action and resource: inspect staged, unstaged, and non-ignored untracked changes and return an affected-test plan with fallback reasons. It distinguishes itself from test-running siblings by saying it runs no tests, though it does not explicitly name nearby tools like diffci_select_tests or diffci_changed_files.

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?

Usage is implied: use this to obtain an affected-test plan and fallback reasons without executing tests. However, the description does not explicitly say when to choose it over diffci_select_tests, diffci_changed_files, or diffci_check, nor does it state exclusions beyond 'runs no tests'.

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