describe_constraints

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

With no annotations provided, the description carries the full burden and does well: it declares 'takes no arguments, read-only', discloses the return shape, and notes the content is derived from the actions registry as the single source of truth matching the validation engine. This is real behavioral context beyond a bare description, though it omits things like caching or versioning.

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?

Front-loaded with the core purpose, then usage, then return shape. The parenthetical enumeration of all 10 type names is slightly verbose but genuinely informative since no output schema exists. No wasted filler.

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?

With no output schema and no annotations, the description compensates fully: it explains what is returned (types array with type/refs/params), the provenance of the data, and the read-only no-arg nature. An agent has everything needed to call and interpret this 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?

The tool takes zero parameters, so the baseline is 4. The description reinforces this with 'takes no arguments' and instead documents the semantics of the returned refs/params fields, which is useful but not parameter guidance per se.

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: list the 10 constraint types Precis supports, and even enumerates them (NotNull/Unique/.../Composite). An agent immediately knows this is a reference-lookup tool rather than a validator or schema inferrer.

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?

Explicitly says to use it 'when writing or editing *.constraint.yaml files, or when unsure which parameters a constraint type accepts', which is a clear triggering context. It does not name or contrast with the sibling tools (validate_data, check_config, infer_schema), but those have distinct purposes so the risk of confusion is low.

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