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

Annotations already declare readOnlyHint=true, but the description adds significant behavioral nuance: it explains how to interpret synergy scores, warns that high deck count with low synergy is often a generic staple like Sol Ring, and distinguishes between popularity and commander-specific synergy. This exceeds what annotations convey.

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 well-structured and front-loaded with the tool's purpose. It uses three packed sentences covering data source, output fields, interpretive guidance, and a usage recommendation. No word is wasted, and the Sol Ring example makes it concrete.

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?

The description covers the data source, output semantics, and how to interpret results, making it sufficient for most users. It is slightly incomplete because it omits the behavior of the optional parameters 'limit' and 'minSynergy', which could be gleaned from the schema names but are not explicitly defined.

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?

With 0% schema coverage, the description must explain all parameters. It clarifies that 'commander' is the target commander via 'with a given commander', but it does not mention the 'limit' parameter (likely a cap on returned cards) or 'minSynergy' (a filter threshold). These gaps are not compensated elsewhere.

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 that the tool returns the most commonly played cards with a given commander, along with deck count, share, and synergy score. It differentiates itself from siblings by emphasizing both popularity and synergy, and explicitly contrasts with 'everyone plays anyway' cards like Sol Ring.

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?

The description gives a clear use case: 'Use this to ground deckbuilding in what people actually play instead of guessing.' It also advises to lead with high-synergy cards when recommending. However, it does not explicitly name alternative sibling tools or state when not to use it.

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