nexus_add_favourite_game

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

Beyond annotations, the description reveals the rate-limit pool trait ('Consumes the v2 GraphQL pool, NOT the v1 REST rate-limit quota') and the exact return shape ('Json {addFavouriteGame: {success}} or an error string'). It also aligns with annotations: readOnlyHint=false and destructiveHint=false are consistent with an add operation.

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?

Three short sections, each earning its place: purpose, pool/rate behavior, and return format. The most important information is front-loaded in the first sentence.

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?

The definition covers the action, API-pool behaviour, return format, and parameter provenance. Minor gaps exist around authentication prerequisites or duplicate-favourite edge cases, but for a single-parameter idempotent mutation these are not critical.

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 the single parameter game_id is already well-described in the schema as coming from nexus_search_games / nexus_get_game. The description adds no parameter-level guidance, so 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 opens with a specific verb and resource: 'Add a game to your favourites via v2 GraphQL.' This clearly identifies the action and differentiates it from siblings like nexus_remove_favourite_game and nexus_get_favourite_games by naming the exact operation.

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?

The description gives relevant context by noting the v2 GraphQL pool and explicitly saying it does NOT consume the v1 REST rate-limit quota. This helps an agent choose it for v2-pool operations, though it does not explicitly compare against sibling tools like remove/get favourite games.

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