Get required fields

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the tool is clearly safe and non-destructive. The description adds no additional behavioral context beyond stating it lists fields, which is appropriate. With annotations covering the safety profile, a score of 3 is reasonable.

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 concise at 4 lines, front-loading the purpose and then providing usage guidance. No unnecessary information. Slightly more verbose than necessary but still well-structured.

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 (1 parameter, output schema exists, low complexity), the description adequately covers purpose, usage, and parameter. No need to detail return values since output schema is available. Complete for its context.

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 100%, and the description's parameter documentation ('message_type: A supported ISO 20022 acmt message type') adds no extra meaning beyond what is already in the schema's description and enum list. Baseline 3 is correct.

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 'List only the required input field names for an acmt message type' with a specific verb (list) and resource (required field names). It explicitly distinguishes from the sibling tool get_input_schema by noting that the sibling provides full type/format constraints.

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 explicitly states when to use this tool ('quick checklist of mandatory columns before building account records') and when not to use it ('when you need full type/format constraints, call get_input_schema instead'), providing clear guidance on alternatives.

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