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

Annotations already declare readOnlyHint=true, so the agent knows this is safe. The description adds behavioral details beyond that: 'Seeded by example rather than by description' and the `limit` default/cap. No contradictions with annotations. However, it does not mention any potential quirks or response structure, but output schema exists.

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 sentences, each serving a distinct purpose: the core function, alternatives/usage, and limit behavior. No redundancy or filler. Front-loaded with the primary purpose, making it easy to parse.

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?

Given that the tool has 7 parameters and zero schema descriptions, the description is not fully complete. It covers the core input (`cardNames`) and `limit`, but leaves multiple filter parameters undocumented. It also does not contrast with the similar sibling `find_combos`, though it does distinguish from `semantic_card_search` and `search_cards`. The presence of an output schema mitigates some completeness gaps.

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 0%, so the description must compensate. It only explains `limit` (defaults to 10, caps at 100) and implies `cardNames` means card names. The other parameters (`types`, `colors`, `format`, `manaValueMax`, `manaValueMin`) are left entirely unexplained, leaving the agent guessing about their allowed values and 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 clearly states the tool's purpose: 'Given one or more cards the user ALREADY has, find cards that work with them.' It uses a specific verb (find) and resource (cards), and explicitly distinguishes from siblings by contrasting 'semantic_card_search instead' and 'search_cards for structured filters.'

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?

Provides explicit when-to-use guidance: 'Given one or more cards the user ALREADY has' and explicitly names alternatives with instructions ('Use semantic_card_search instead to describe a desired effect in words, and search_cards for structured filters'). Also includes the `limit` default and cap, adding practical usage context.

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