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

Annotations already establish read-only, open-world, non-idempotent, non-destructive behavior. The description adds valuable context beyond that: result cap of 20, Oracle text in results, null prices when unknown, affiliate links, required shopping-link disclosure, and that search is bounded rather than exhaustive.

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 compact and front-loads the core purpose before listing constraints and result details. It is slightly run-on and contains a spacing typo ('up to20'), but nearly every sentence carries useful information.

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?

With no output schema and low schema coverage, the description does a good job explaining return contents and special behaviors. It covers the key input semantics and output caveats, though it leaves `limit` behavior implicit and does not explain error or empty-result behavior.

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 only 20%, so the description must compensate. It does so well for `query` (card names or Scryfall syntax), `colors` (blank/C means colorless only; omitted means any identity; repeated letters canonicalized), and `maxPriceUsd` (USD per-card price cap). It does not explain `limit` or `qaTest`, but `qaTest` is the one schema-described parameter.

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 gives a specific verb and resource: 'Search card names or Scryfall syntax,' and the title adds 'Commander-legal cards.' It does not explicitly contrast with the sibling `search_commanders`, so it is clear but not fully differentiating.

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?

It provides useful semantics for the `colors` parameter ('C or blank colors means colorless only; omit colors for any identity'), which implies usage. However, it never states when to use this tool instead of `search_commanders` or other siblings, and there are no explicit exclusions.

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