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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is fully covered. The description does add value by disclosing that results include a probability of being the club's main taker, but it says nothing about default coverage (all 20 clubs), result grouping, or how the probability is expressed — with no output schema, that leaves the return shape only partly characterized.

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?

One front-loaded sentence with no filler, and the set-piece scope plus the probability output are stated up front. The closing clause ('chance of being his club's main taker') is slightly wordy but still earns its place by signaling return content.

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?

A low-complexity read tool with one optional parameter, rich annotations, and no output schema — the description covers the domain (Premier League/FPL), the set-piece categories, and the probability field. Only the result structure and the all-clubs default are unaddressed, which is minor here.

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 single 'teams' parameter is documented in the schema with an example and the default of all 20. The description never mentions the filter at all, so it adds no meaning beyond the schema; 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 ('find') and resource ('penalty takers, corners and free kicks') for Premier League clubs in FPL, and usefully widens scope beyond the tool name/title, which says only 'penalty takers'. It doesn't distinguish itself from general player-lookup siblings like find_players, but no sibling appears to cover set-piece duty specifically.

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?

'Use this to find who takes penalties...' gives an implied usage context, but there is no statement of when-not to use it or which sibling to prefer (e.g., find_players or get_player for general player data). Usage must be inferred from the set-piece framing alone.

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