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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the exact fields returned, that start times are UTC while the date parameter is league-local, the status vocabulary, and the API-key requirement. It doesn't mention pagination or result limits, keeping it out of 5 territory.

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?

Two short sentences with no filler; the returned-field list is front-loaded and the API-key caveat is placed last. The noun-phrase style is terse but readable, with only the trailing '...' in the status list being slightly loose.

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?

With no output schema, the description usefully enumerates the return fields, and the API-key prerequisite is stated. For a two-parameter read tool whose annotations cover safety, that is nearly complete; only result-size/pagination behavior is unaddressed.

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%, so the schema already documents both parameters including the date format, 31-day range cap, and league codes. The description only restates 'on a date' and adds the UTC contrast for start times, adding little beyond structured data. Baseline 3 applies.

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 (a league's schedule/fixtures on a date) and enumerates the returned fields (ids, UTC start times, teams, status, postponement links), which is specific enough to distinguish it from siblings like get_live or get_consensus. It lacks an explicit verb and never names a sibling it is not, so it stops 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 only implied: an agent can infer this is the tool for a league's schedule on a date. The one explicit operational note, "Needs an API key," is a prerequisite rather than when-to-use guidance. No exclusions or comparison with get_live (live scores) or list_leagues are given.

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