Get file coverage

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

The readOnlyHint annotation already signals safety, and the description adds a behavioral dependency: the tool relies on a prior get_coverage_report run to have data. This is meaningful context beyond the annotation, though error behavior for missing reports is not disclosed.

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?

A single sentence that is front-loaded with the core action and resource, with no redundant wording. It is concise and structured effectively.

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 tool is simple (one required parameter, three optional) and the description covers purpose, prerequisite, and output. No output schema is present, but the description states what is shown. Minor gap: it does not mention what happens if the coverage report is absent, but for a read-only tool this is acceptable.

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 the baseline is 3. The description adds no parameter-specific detail, but the schema already fully documents 'file', 'module', and 'projectDir' with examples.

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 ('Show') and resource ('covered/uncovered line numbers of one source file'), clearly stating what the tool does. It also distinguishes from the sibling get_coverage_report by referencing the 'latest coverage report' as the data source.

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?

It explicitly states a prerequisite: 'run get_coverage_report first', which conveys when to use the tool. It does not explicitly name alternatives or exclusion criteria, but the prerequisite provides sufficient contextual guidance.

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