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

Annotations already cover readOnly/idempotent, so the description adds real value on top: a freshness SLA (at most 1 s old), the coverage window (next 24 hours plus in-play), the meaning of a 'recent false' result (no current consensus), and an auth requirement (needs an API key). It still does not describe the shape of the response or behavior when league/fixture are omitted, so it stops short of a 5.

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?

Three short sentences, front-loaded with the payload definition, with no filler. The sentence 'recent false means no current consensus' is slightly cryptic because 'recent' is never otherwise introduced, but it is compact rather than wasteful.

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 returns; it covers the outcome-to-probability mapping and the 'recent' flag at a high level but not the full response structure (e.g., per-fixture grouping, timestamps). For a 2-param read tool with annotations, it is adequate but leaves gaps on return shape.

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%, including the league enum list and the fixture id format with a pointer to list_fixtures. The description adds no parameter-level meaning beyond that. Baseline 3 is appropriate when the schema carries this burden.

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 names the resource and its payload precisely: a market-implied probability per outcome (home, away, draw). It also scopes the data to games starting within 24 hours or currently in play. It does not explicitly distinguish itself from siblings such as get_live or get_sample, so it falls short of a 5.

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?

Usage is implied through the scope statement (games within 24h and live games, data at most 1 s old), which tells the agent when the data is valid. However, it never says when to prefer this tool over get_live or get_sample, nor any exclusions. An agent must infer the routing decision.

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