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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the description's closing 'Read-only.' largely restates structured data rather than adding to it. It does add value by disclosing the output contents (percentage, lines, trend direction), but says nothing about aggregation scope, staleness of coverage data, or behavior for repositories with no coverage data.

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?

Two sentences, front-loaded with the resource and returned fields before the use case, with no filler. The trailing 'Read-only.' is redundant with the annotations and could be cut, which keeps it just short of a 5.

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 zero-required-parameter, single-filter read tool with an already safe annotation profile, the description covers purpose, returned metrics, and interpretation. The only meaningful gap is the absence of return-shape detail (no output schema exists) and no statement on how repos without coverage data appear.

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 single repositoryId parameter is already documented as 'Filter to a specific repository by ID. Omit to see all repositories.' The description adds no format, syntax, or defaulting information beyond that, 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?

States a specific verb and resource ('Get test coverage summary per repository') and enumerates the returned metrics: overall coverage percentage, lines covered, and trend. This distinguishes it from sibling summary tools like get_dora_summary or get_ai_adoption_summary, which cover different health dimensions.

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 gives an implied use case ('understand testing health and identify repositories with low coverage that may warrant additional review attention'), but never names an alternative tool or states when not to use it. There is no guidance on pairing it with get_repository for drill-down, so the agent must infer routing from the sibling names alone.

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