start_experiment

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

Behavioral traits are disclosed beyond the minimal annotations: it explains the auto-read of git HEAD if git_ref is omitted, and clarifies that the server stores verdicts not loss curves. This adds valuable context that annotations (idempotentHint=false, destructiveHint=false) do not provide. No contradiction with annotations.

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 long with no wasted words. The first sentence states the purpose efficiently, and the second adds two key behavioral details. It is front-loaded and every sentence earns its place.

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?

Given the tool has 5 parameters (1 required), minimal annotations, and an output schema, the description covers the key aspects: purpose, git_ref behavior, and external run relationship. It does not explain the output format, but since an output schema exists, that is acceptable. It is complete enough for an agent to use the tool correctly, though it could mention that it creates a new experiment record.

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 40% (2 of 5 parameters have descriptions in schema). The description adds meaning for git_ref (auto-read from HEAD) and external_run (reference to W&B/MLflow run). However, for the other parameters (id, config_note, hypothesis_id), no additional semantics are provided beyond the schema. This partially compensates for the low coverage but not fully.

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 clearly states 'Begin testing a hypothesis.' It uses a specific verb (begin) and resource (hypothesis). It also distinguishes itself from sibling tools like 'propose_hypothesis' by indicating it initiates the testing phase. The added details about git_ref and external runs further clarify its scope.

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 provides context about when to use the tool (when you want to begin testing) and mentions the external run reference, but it does not explicitly contrast with sibling tools or state when not to use it. There is no guidance on prerequisites or alternatives.

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