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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the burden is lower. The description adds meaningful behavioral context by disclosing that results may come from a static_seed adapter (group schedule only) when live providers are unavailable, and it outlines the response fields including pagination and meta.source. This goes beyond the annotations without contradicting them.

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 well-structured with a front-loaded purpose sentence followed by Args and Returns sections. Some redundancy exists because the Args block duplicates the schema and the output schema already documents return values, but overall it remains compact and readable.

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?

For a simple paginated read-only fixture tool, the description is complete: it explains the data source fallback, pagination semantics, and return shape via structured sections. With annotations covering safety and an output schema present, an agent has everything needed 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?

Schema description coverage is 100% and the description repeats the limit and offset documentation almost verbatim. It adds no new meaning beyond what the input schema already provides, so the baseline 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 opens with a specific verb and resource: 'Return World Cup 2026 fixtures', which clearly identifies the tool's purpose. The parenthetical 'live providers, else the group schedule' adds useful scoping, though it does not explicitly contrast with sibling tools like football_get_groups or football_get_standings.

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?

The description gives a clear context for use: it is the fixture-list tool, with the data source conditionally explained as live providers or the group schedule. It does not name alternatives or exclusions, but among the football siblings there is no other direct 'get fixtures' tool, so the intended usage is reasonably clear.

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