Returns surviving mutants from a mutation-testing run with file, line, operator, before/after code, and an actionable hint, plus offset/limit pagination for large results.
Run the analysis and return surviving mutants only, with file, line, operator, before/after code, and a hint. Supports offset/limit pagination.
| Name | Required | Description | Default |
|---|---|---|---|
| all | No | ||
| diff | No | ||
| jobs | No | ||
| root | No | ||
| limit | No | Default: 25. | |
| offset | No | Default: 0. | |
| sample | No | Default: 60. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It discloses that the tool runs analysis and returns survivors with specific fields and pagination, but it does not explain runtime cost, prerequisites such as a configured mutation setup, whether tests are executed, or side effects.
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 sentences, front-loaded with the main action and output, with no filler. Its brevity is appropriate structurally, even though it leaves behavioral and parameter gaps.
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 7-parameter analysis tool with no annotations and no output schema, the description is too incomplete. It partially compensates by listing returned survivor fields, but it omits key parameter semantics and behavioral context needed to invoke the tool correctly.
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 only 43%, so the description should compensate for undocumented parameters. It mentions offset/limit pagination, which is already in the schema, but does not explain all, diff, jobs, root, or sample beyond their names and basic types.
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: run analysis and return surviving mutants only, including concrete output fields. It is clear enough to distinguish from a mutation score tool, though it does not explicitly name the sibling tools it differs from.
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 implies this is for listing surviving mutants, but it gives no explicit when-to-use guidance, no exclusions, and no reference to alternatives such as fang_mutation_score or fang_check_diff. The agent must infer the routing from the tool name and brief purpose.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.