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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered; the description goes further by disclosing source-side defaults, that full mode returns a data-only envelope ignoring paging controls, that omission preserves the underlying API default, and that the tool performs no local calculation or account tracking. The unusual include_cosmetics caveat (a widening option, not an exclusive type predicate) is exactly the kind of non-obvious behavioral trait that prevents misreading results. It stops short of stating rate limits, ordering, or failure behavior.

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 first sentence crams purpose, options, return contents, and preservation guarantees into one long chain, and the include_cosmetics caveat is restated at length in both description and schema. The information is front-loaded and mostly earns its place, but the density and duplicated caveat make it harder to scan than it needs to be.

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 read-only list endpoint with a full-coverage input schema, an output schema, and annotations covering safety, the description supplies the remaining needed context: source default resolution, full-mode envelope behavior, and explicit non-capabilities. The one gap is routing guidance against the singular evolution sibling, which an agent must guess at.

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 baseline is 3. The description's parameter content (include_cosmetics semantics, no_pagination full-list mode, page/page_size defaults) duplicates the schema text nearly verbatim rather than adding derivation rules or interaction notes. It adds little meaning an agent could not read directly off the input schema.

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 opening clause states a specific verb+resource ('Browse native FC27 evolution metadata') and enumerates the selectable axes (expiry, cosmetic, name, pagination) plus what the rows contain. The closing sentence carves out non-goals ('No eligible-player or path generation, account tracking or local calculation'), which sharpens scope. It never names or contrasts with the singular sibling futgg_fc27_evolution, so differentiation is inferential rather than explicit.

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?

Conditional behavior is spelled out for the key switches (no_pagination=true gives the data-only full list; omitted page resolves to page 1; nonpositive page_size resolves to 30), which implicitly tells an agent how to pick settings. However, there is no when-to-use guidance relative to the other evolution/catalog tools in the sibling list, and no statement of what query an agent should prefer this tool for. Usage is implied by parameter semantics rather than declared.

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