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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and openWorld, so the safety profile is fully covered. The description adds one genuinely useful behavioral fact not in structured data — that omitting both team and league defaults to the Premier League — but says nothing about return format or the 404 behavior hinted at in the schema.

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 core purpose, then example queries, then the default — logical ordering with little waste. The leading 'Form Guide.' fragment is slightly redundant with the title but functions as a fast domain signal.

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 read tool with no output schema, full parameter documentation, and safety annotations, the description covers purpose, triggers, and the default fallback adequately. The only omissions are return shape and error handling, which are minor for this tool's complexity.

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 each parameter already carries a clear description (range for 'n', example club names, allowed league list). The prose adds no syntax, formatting, or precedence detail beyond what the schema supplies, so the 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?

States a specific verb+resource ('Latest results for a club, or the last round of a league') and the example queries pin down intent precisely. It implies but never explicitly distinguishes itself from siblings like formguide_get_fixtures or formguide_get_table, so an agent must infer that this is past results rather than upcoming or 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?

Gives concrete trigger phrasing ('how did Chelsea get on?', 'what were the Serie A results?') and documents the no-argument fallback to the Premier League. It stops short of naming alternative siblings or stating when NOT to use it, so no exclusions are provided.

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