MTG Bench

search_cards

Read-only

Find cards by NAME or by structured filters (colors, color identity, types, mana value, format legality, sets). Use when the query can be expressed as filters: "red instants under 3 mana", "legendary artifacts in Standard", "cards named Bolt". Use semantic_card_search instead when the user describes an EFFECT rather than a filter ("cards that make a treasure when I attack"). Use find_synergies instead when they name cards they already have and want things that pair with them. Searches every Magic card; use search_my_collection to search only what the user owns. limit defaults to 25 and caps at 100 per call.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "search_cards"
  }
}

Input Schema

Name	Required	Description	Default
`name`	No
`sets`	No
`limit`	No
`types`	No
`colors`	No
`format`	No
`supertypes`	No
`manaValueMax`	No
`manaValueMin`	No
`colorIdentity`	No

Output Schema

Name	Required	Description	Default
`cards`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedAug 9, 2026

TDQS

A4.6/5.0

Behavior4/5

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

The annotations already provide readOnlyHint=true, so the read-only nature is known. The description adds valuable behavioral context by stating that it searches every Magic card and that limit defaults to 25 and caps at 100. This goes beyond the annotations without contradicting them.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is four sentences long, front-loaded with the core purpose, and every sentence contributes meaningful information. There is no fluff or repetition of schema details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return value details are handled elsewhere. The description covers the tool's scope, filter types, limit behavior, and provides clear alternatives. It is sufficiently complete for an agent to use the tool effectively, with only minor omissions like supertypes.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0% schema description coverage, the description compensates by naming the primary filter categories: colors, color identity, types, mana value, format legality, and sets. It also explains limit behavior. However, supertypes is not explicitly mentioned, and the types/supertypes distinction is left implicit, which is a minor gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool finds cards by name or structured filters, enumerating filter categories such as colors, types, mana value, and format legality. It distinguishes itself from sibling tools like semantic_card_search and find_synergies, so the agent knows exactly what this tool does.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives explicit usage guidance, stating to use this tool when queries can be expressed as filters, and directs to semantic_card_search for effect-based queries, find_synergies for pairing with existing cards, and search_my_collection to limit to owned cards. This is exemplary decision support.

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

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