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

With annotations only declaring readOnlyHint=false and destructiveHint=false, the description adds real behavioral context: an implicit side effect (a golden suite is auto-generated if none exists), fluke detection for suspected regressions, and a per-scenario pass/fail return shape. It stops short of covering permissions, cost, or latency.

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 action and intent, then the enumeration of variant modes. Dense but each clause carries information; the only mild redundancy is restating the return/pass-fail behavior already implied by the name.

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, and the description compensates by describing the return payload (pass/fail per scenario plus fluke detection) and the auto-generation side effect. Combined with full schema coverage of parameters, an agent has what it needs to invoke this 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?

Schema coverage is 100%, so the baseline is 3, but the description adds cross-parameter guidance the schema cannot: the three variant-specification modes and their mutual exclusivity. It still defers per-param semantics (e.g., customerId scoping) to the schema.

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 ('Run regression test for a prompt variant against its golden test suite') and immediately frames the intent — protecting existing functionality. It is clearly distinguishable from siblings like validate_variant, get_regression_suite, or add_regression_scenarios.

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?

Gives a clear context for use ('ensure it doesn't break existing functionality') and explains the three mutually exclusive ways to specify a variant. It does not, however, explicitly contrast this tool with the nearest alternatives such as validate_variant or get_regression_suite.

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