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

Beyond the read-only/non-destructive/open-world annotations, the description discloses non-obvious behaviors: a level name starting with ATP/WTA fixes the tour and contradicting tour= arguments are rejected, and the source cannot separate ATP 500 from ATP 250. It also reports parallel-safety and upstream cost, which no annotation conveys.

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 one-line purpose followed by clearly labeled When-to-use, Prefer-over, and Do-not-use sections, so it is scannable. Slightly longer than necessary, with the level examples repeated ("WTA 1000" appears in both the usage and semantics blocks).

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?

Output schema already documents the return shape and annotations cover the safety profile, so the description is free to focus on selection guidance, which it does thoroughly, including domain caveats an agent could not infer from the schema alone.

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 structured fields are already documented and baseline is 3. The description earns above baseline by explaining semantics the schema does not: that level accepts names or raw tier codes (G/M/A/C/D), and the level/tour interaction rule that would otherwise be invisible.

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+resource ("Tennis tournament catalog: find tournaments") plus the exact filterable dimensions, and explicitly distinguishes itself from siblings event_card and call_api. An agent can tell instantly what this returns versus the bracket/edition tool.

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 concrete when-to-use example queries, names the alternatives (event_card, call_api) with the condition that selects them ("when you do NOT already have a tournament id"), and adds an explicit do-not-use section redirecting bracket and calendar needs to event_card. This is the full when/when-not/alternative triad.

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