lookup_card

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

No annotations are provided, so the description carries full burden. It discloses return fields, null return on no match, and the fuzzy vs. exact search behavior. Could mention rate limits or Scryfall API details, but for a read-only lookup it is adequately transparent.

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?

Two sentences plus a list of return fields, all front-loaded. Every sentence adds value: purpose, use cases, and parameter clarification. No wasted words.

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 the tool's simplicity (2 params, output schema exists), the description covers all essential aspects: purpose, return values, behavior on no match, and parameter options. The output schema covers return format, so no additional explanation needed.

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 0%, so description must compensate. It explains the 'exact' parameter (set to true for exact match, default fuzzy) and the 'name' parameter implicitly as card name. Adds meaning beyond schema names, though 'name' could be more explicitly described.

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?

Description starts with 'Resolve a Magic: The Gathering card name via Scryfall,' clearly stating the verb-resource pair. It distinguishes from sibling 'search_card' by focusing on resolving a single name with fuzzy/exact matching, and lists key return fields (canonical name, set, oracle text, mana cost, image URL, Scryfall URI).

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 usefulness for 'disambiguating reprints, validating spelling, or fetching multilingual names,' providing clear context for when to use. Does not explicitly mention when not to use or compare to siblings, but the context is sufficient for the agent.

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