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

The description adds behavioral context beyond the readOnlyHint annotation by specifying the exact API path (GET /account_numbers) and detailing how filters are sent (e.g., 'status.in'). It does not cover all behaviors like pagination details (though the schema covers limit and cursor) or rate limits, but the added info is valuable for understanding the API interaction.

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 brief, at two sentences, and front-loads the core action. While it could be more structured (e.g., using bullet points for filters), it avoids unnecessary detail and is efficiently written. Every sentence contributes value, and there is no 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?

Given the tool's simplicity (list operation), the description provides the essential purpose and filtering context. However, it lacks details about the response format or pagination behavior beyond the cursor parameter. Since there is no output schema, the description could have included what the response contains (e.g., object array with id, routing, account number). Still, for a straightforward list tool, it is minimally adequate.

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 100% schema description coverage, the baseline is 3. The description adds value by clarifying that the status parameter is sent as 'status.in' in the query string, which is not obvious from the schema alone. This helps the agent correctly construct the API call. The other parameters are adequately described in the schema, so the overall parameter semantics are well-served.

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 verb 'List', resource 'account numbers', and explains they are 'deposit routing/account number pairs'. It also mentions the API endpoint and filtering options, making the purpose unmistakable. This distinguishes it from sibling tools like 'increase_list_accounts' which lists accounts themselves.

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 indicates the tool lists account numbers with optional filters, implying its use for retrieving such data. However, it does not provide explicit guidance on when to use this tool versus alternatives (e.g., when account IDs are known vs. needing to list all), nor does it state when not to use it. The context of sibling tools helps but the description itself lacks explicit usage recommendations.

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