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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely useful non-annotation context: return field list (slug, name, date, local start time + timezone, venue, status, bout counts), parallel-safety, and upstream cost of 1. It doesn't explicitly note rate limits or pagination beyond the limit param.

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 one-line purpose, then scannable usage bullets, then behavior notes, then example. Every line earns its place, though the metrics block (parallel-safe, upstream cost) is a bit of an internal artifact rather than agent-facing prose.

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 exists so return shape needn't be described, yet the description still enumerates the key return fields. For a 3-param read-only list tool with full schema coverage, nothing an agent needs to call it correctly is missing, and it routes to the right sibling.

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% and every parameter has a description with an enum and examples, so the schema carries parameter meaning. The description adds only an example call showing typical values, not new semantics. Baseline 3 is correct.

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 ('upcoming cards or recent results') with the exact leagues named (RAF wrestling, BKFC bare-knuckle). The 'Getting an event slug for combat_card' line clearly distinguishes it from combat_card, which takes the slug this tool produces.

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?

Explicit when-to-use with example queries ('When is the next RAF / BKFC card?'), explicit 'Prefer over: call_api /raf/events', and explicit 'Do not use when: you already have the event slug'. All three when/when-not/alternative conditions are present.

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