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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description goes beyond them usefully: it discloses the filter dimensions (buyer type, price, audience, reachable buyers, budget, buildability), the ranking criterion (evidence strength vs cost and days), and the full return contract (sample, steps, pass line, kill line, inconclusive rule, decision date, backup test, ruled-out tests with reasons).

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 purpose is front-loaded and the output contract is valuable, but the middle sentence is a very long run-on that crams the whole 18-test library (with 11 examples) into a parenthetical. The test-name enumeration is bloat the agent does not need in order to invoke the tool.

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?

There is no output schema, so the description must carry the return contract, and it does so thoroughly (sample, steps, pass line, kill line, inconclusive rules, decision date, backup test, ruled-out tests). Combined with 95% schema coverage on 19 parameters and annotations covering safety, nothing essential for correct invocation is missing.

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 95%, so the schema already documents each of the 19 parameters, including defaults. The description restates the filter inputs and the riskiest-assumption default without adding syntax or per-parameter meaning beyond the schema, which is exactly the baseline-3 case.

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 concrete verb+resource (pick/plan a validation test from a named library) and specifies the selection logic (cheapest test that can falsify one assumption within days available). It enumerates 11 of the 18 library tests for concreteness. It never differentiates itself from siblings like kill_or_continue or cut_mvp, so it stops short of a 5.

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?

Usage is implied rather than stated: the agent can infer it should call this when it needs to choose a validation experiment under day/budget constraints, and the 'Defaults to the riskiest assumption; pass assumption to choose another' line hints at preconditions. But there is no explicit when-to-use/when-not and no routing to or away from sibling tools.

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