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

With no annotations, the description carries the burden. It adds meaningful context about the contents of the record (all rails, payment endpoints, OP attestation) and discloses an authentication requirement (Tier 2+ requires AT credential). It does not mention side effects or error conditions, but as a read operation, the 'get' verb implies safety.

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 two sentences, each adding value. The first sentence front-loads the core action and scope, and the second provides a concise access requirement. No fluff or redundancy.

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?

For a simple getter with one parameter and no output schema, the description is fairly complete. It explains what the record contains and the authentication prerequisite. It does not describe the response structure, but the listed contents give an adequate overview for a tool of this complexity.

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?

The input schema has one required 'id' parameter with no description (0% coverage). The description does not explicitly explain the parameter, but the phrase 'one merchant' gives context that 'id' is the merchant identifier. This is minimal compensation for the lack of schema description, falling short of fully detailing parameter format or constraints.

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 the action ('Get'), the resource ('the full record for one merchant'), and the specific contents (all rails, payment endpoints, OP attestation). This distinguishes it from siblings like search_merchants (search vs. get) and list_categories/list_rails (which list subsets).

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 implies when to use it: when you need the full record for a single merchant, as opposed to search or listing. It provides a clear context but does not explicitly mention alternatives or exclusions. The credential requirement is a usage constraint, but not a comparison to siblings.

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