Search MTG cards (free, Scryfall)

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real value beyond that: no credentials needed, free tier, and the exact return payload (ids, set info, USD/EUR/TIX prices, Cardmarket/TCGplayer product ids). It omits rate limits and pagination, keeping it below a 5.

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 tight sentences with no waste and the key differentiator ('FREE tier') front-loaded. The example is well placed, though 'FREE tier. Requires no credentials' is mildly redundant with the later sentence.

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 only 3 params, no output schema, and light annotations, the description does the heavy lifting by enumerating return fields and credential requirements. It's not fully complete because the meaning of 'unique' and 'limit' behavior (caps, defaults) is never addressed.

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 33%: only 'query' is documented, and the description compensates usefully with a Scryfall syntax example ('o:flying t:dragon'). However, 'limit' and 'unique' are left unexplained in both schema and description, so the gap is only partly filled.

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 Magic cards') and specifies the mechanism ('Scryfall syntax') with an example. It distinguishes itself from the paid-API siblings by noting the returned product ids are 'for use with the paid-API tools', though it doesn't name any sibling explicitly.

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?

Clear context is given: this is the 'FREE tier' tool that 'requires no credentials', implicitly positioning it ahead of the paid cardmarket/tcgplayer tools for discovery. It doesn't give explicit when-not or name a specific alternative to use instead, so it stops short of full routing guidance.

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