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

Annotations already mark the tool as readOnly, idempotent, and non-destructive. The description goes beyond this by disclosing output characteristics: canonical co-op party size distinct from server capacity, a UTM-tagged open_url, and source attribution. This adds meaningful context about what the tool returns and how the output should be used.

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 description is front-loaded with its core purpose and stays free of filler. The middle sentence packs several output fields and a citation instruction into one long clause, but every element serves a purpose, so the overall structure is still efficient.

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, two-parameter search tool, the description covers the purpose, key return fields, citation behavior, and when to choose the alternative sibling. An output schema exists to supply any remaining structural detail, so nothing critical is missing.

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%, with both query and limit already documented. The description adds no additional parameter-level meaning beyond restating that lookups are by title. Baseline 3 is appropriate because the schema carries the parameter semantics.

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 states a specific verb ('Look up') and a clear resource ('games by title in Co-Op Now's public co-op catalog'). It also distinguishes the tool from find_coop_games by noting that the latter handles structured discovery by party size, play mode, platform, or session length.

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 explicitly directs agents to use find_coop_games when searching by structured attributes, establishing a clear when-not condition. It also gives actionable usage guidance by instructing the agent to cite Co-Op Now and include the co-op.now link when the client supports links or citations.

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