detect_runner

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

With no annotations, the description carries the full burden and does substantial work: it declares the read-only nature, enumerates what evidence is gathered per candidate, and explains that readiness depends on pytest being importable or node_modules existing. It stops short of saying what happens when nothing is detected or how costly the scan is.

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 key scoping claim is front-loaded in the first sentence, followed by supporting detail about what is inspected and returned. It is slightly long and the trailing parameter lines are terse fragments, but no sentence is padding.

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 two-parameter, read-only detection tool with an output schema, this covers what it inspects, how readiness is judged, interpreter resolution, and even test directories. The only real gap is the no-runner-detected case, a minor omission given the return schema exists.

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 coverage is 0%, so the description must compensate, and it does: 'path' is described as the project root with the advice that absolute is safest, and 'python' is described as an optional interpreter path or the literal 'uv'. Both parameters get meaning the bare schema lacks, though the exact 'uv' behavior is left implicit.

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 — 'Detect which test runner a project uses' — and immediately scopes it with 'without running any of its tests', which cleanly separates it from run_tests and rerun_failed. An agent can pick this out of the sibling list without opening the schema.

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 phrase 'without running any of its tests' implies a pre-flight/inspection use, and the readiness checks hint that this precedes actual execution. However, no sibling is named, no explicit when-to-use or when-not-to-use rule is given, and the agent must infer the relationship to run_tests or list_tests.

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