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

Annotations already declare readOnlyHint=true, and the description reinforces this with 'No credentials needed.' It adds valuable behavioral context beyond the annotation: the integer minor-unit convention (100000 means 1000.00 EUR) and the explicit statement that no authentication is required. This is useful for an agent deciding whether to call this tool without setup.

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 short sentences, each carrying distinct information: what the catalogue contains, that no credentials are needed, and the integer minor-unit convention. No filler, no repetition of the schema, and the most important scoping information is front-loaded.

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 zero-parameter read-only tool, the description is nearly complete. It covers the resource, the data fields, the currency format, and the authentication requirement. The only minor gap is that it doesn't describe the exact response structure (e.g., whether it's a list or object), but with no output schema and a simple catalogue read, this is a small omission.

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 tool has zero parameters, so the schema is trivially complete. The description adds meaning by explaining the return semantics (integer minor units, currency), which is the only parameter-like ambiguity an agent might face. With 0 params, the baseline is 4, and the description earns it by clarifying the data format.

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 states a specific verb ('Read') and resource ('service catalogue'), and enumerates exactly what the catalogue contains: names, prices, currency, and terms. This clearly distinguishes it from the sibling tools, which are all action-oriented (accept_offer, create_order, start_payment) or status-related (order_status, manifest).

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 implicitly signals when to use this tool: when an agent needs catalogue data (names, prices, currency, terms) before making decisions like creating an order or starting a payment. It doesn't explicitly name alternatives or exclusions, but the read-only nature and the sibling set make the usage context clear.

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