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

Annotations already declare readOnly, non-destructive, closed-world, so the description does not need to argue safety. It adds real behavioral context beyond them: a hard cap of 20 results and the fact that each returned copy carries its version marketPriceEur, which tells the agent about result shape and truncation risk.

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 sentences, front-loaded with the most important distinction (own binder vs catalog) and free of filler. The telegraphic fragments ('Max 20 results.') read tersely but cost nothing in comprehension.

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 five-parameter, single-required-parameter search with no output schema, the description covers scope, result cap, and what a result row contains, which is most of what matters. The remaining gap is that matching semantics for the free-text q and the game/language filters are left entirely to the schema, which documents neither.

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 only 40%, and only the version and condition parameters are documented in the schema. The description compensates partly by noting that free-text queries 'understand version phrases (édition 1, reverse)', which meaningfully explains how q interacts with the version filter. It still says nothing about game or language, leaving two undocumented parameters unaddressed.

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 and resource ('Search cards') plus the exact scope ('inside the user's own binder, not the public catalog'), which immediately separates it from lookups against the public catalog such as lookup_card. An agent can route on this without opening the schema.

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 negative scoping ('not the public catalog') tells the agent when this tool is the wrong choice and implicitly points at catalog lookup siblings, though it never names them. It does not address how it differs from collection_listing siblings like list_doubles or collection_summary, so some inference remains.

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