Step 5: run the test

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

Annotations already declare readOnlyHint=true, destructiveHint=false, so safety is covered; the description adds the non-obvious behavioral fact that the call takes no inputs and instead recomputes from state confirmed in step 1, plus the exact result fields returned. It does not state what happens when prerequisites are missing (error vs empty result), which matters given idempotentHint=false.

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 step number and the action, then the outputs and prerequisite. No filler and nothing that could be cut without losing information.

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, the description compensates by listing the returned fields, and it states the workflow prerequisite. What remains unstated is the failure behavior when steps 1–4 are incomplete and whether re-running alters state, both relevant to a computation marked non-idempotent.

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?

There are zero parameters, so the baseline is 4. The description usefully explains why: the call is driven entirely by the test, columns and hypotheses confirmed in step 1 rather than by arguments, which tells the agent not to look for input fields.

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 (runs) and resource (the test) plus the exact scope: 'exactly the test, columns and hypotheses the user confirmed in step 1.' That scope phrase implicitly separates it from choose_test and check_assumptions in the sibling list, which select or validate rather than execute. It also enumerates the outputs (statistic, p-value, effect size, CI, verdict), so an agent knows what comes back.

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?

'Requires steps 1–4' gives an explicit prerequisite and the 'Step 5' framing makes the position in the workflow unambiguous. It does not name alternatives or say what to do if prerequisites are unmet, so it stops short of full when/when-not guidance.

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