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

Annotations only declare readOnlyHint and openWorldHint; the description supplies the real behavioral gotcha — that response richness depends on profile_type, with basic profiles lacking all statistics. That conditional payload is exactly the kind of trait annotations cannot express and is the main source of agent surprise.

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 return payload, then the profile_type caveat, then id provenance and alternatives — a sensible order with no filler. Slightly dense and the id-source list partially duplicates the parameter description, but nothing is wasted.

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 an output schema present, the description need not enumerate return structures, yet it still flags the profile_type-dependent variability. Combined with 100% schema coverage and readOnly annotations, an agent has everything needed to call this 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 single player_id parameter is already documented in the schema with the same source-tool provenance the description repeats. The description adds no id format, validation, or error semantics beyond what structured fields provide, 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?

Opens with a specific verb and resource ("Returns a player's public profile") and enumerates the exact fields returned. It goes further by splitting the response shape by profile_type (full vs basic), so an agent knows precisely what it will get, and it names the two sibling tools it is not (fussballde_player_matches, fussballde_team).

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?

Explicitly states where valid player ids come from (player search, scorer lists, squads, amateur statistics) and gives a clear routing rule: use fussballde_player_matches for match-by-match data or fussballde_team for the team. This is the when-to-use / when-to-use-something-else pattern done correctly.

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