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

Annotations already mark the tool as readOnly, idempotent, and non-destructive. The description adds meaningful behavioral context beyond that: it performs no network fetch, incurs no cost, requires no key, and returns a specific set of derived values including the exact smb_id. This tells the agent exactly what side effects to expect (none) and what output to anticipate.

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 description is dense but every sentence adds value: what it does, what it avoids, what it returns, and when to use it. Key behavioral constraints are front-loaded, and the '[free, no key]' tag is a compact useful addition.

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?

Given a single parameter, no output schema, and rich annotations, the description is complete. It names the return fields (platform, smb_id, channels, country), clarifies cost and safety, and situates the tool within the surrounding workflow. An agent has enough to invoke 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?

The input schema already documents the single url parameter with 100% coverage, including an example. The description does not materially add parameter-level semantics beyond classifying it as a booking URL, so the baseline score of 3 is appropriate.

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 uses a specific verb ('pre-flight check', 'classifies') tied to a concrete resource (booking URL) and names the downstream dependent tool (import_booking_url). It clearly differentiates itself from sibling tools like schedule_appointment by framing itself as a check that happens before any paid action.

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 instructs when to use it: 'BEFORE calling import_booking_url + schedule_appointment' and why: to 'de-risk a paid booking'. It also states what it does NOT do ('WITHOUT fetching the page or spending money'), giving the agent clear usage boundaries.

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