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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is partly covered. The description goes further by confirming nothing is sent or logged and by describing the report contents: per-variant condition match status and probabilities for weighted endpoints. That is meaningful behavioral disclosure beyond the 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?

Two sentences, both earning their place: the first defines the dry-run preview and its reporting behavior, the second routes the agent to the relevant workflow. No repetition or 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?

There is no output schema, so the description must explain return content — and it does, covering matched endpoint, response selection rationale, variant condition match status, and weighted probabilities. Combined with full schema coverage and safety annotations, an agent has enough to call it 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 description coverage is 100% across five parameters, so the schema already documents method, path, headers, body, and workspace. The description does not add syntax or semantic detail beyond the schema (e.g., it does not explain the X-APIMock-Variant forcing header). Baseline 3 is appropriate when the schema carries parameter semantics.

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 states a precise verb and resource: preview which endpoint and response a request would resolve to, and explains the 'why'. It explicitly distinguishes this preview behavior from siblings like create_endpoint, update_endpoint, and delete_endpoint by emphasizing 'without sending it or logging anything.'

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?

It gives clear usage context — use this to check response variants after create_endpoint or update_endpoint — and clarifies the dry-run nature. It does not name explicit when-not conditions or a full set of alternatives, but the routing guidance is concrete.

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