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

Since no annotations are provided, the description fully carries the transparency burden. It discloses case-insensitivity, the effect of omitting the parameter, and that 'MT103 and pacs.008 responses include a tracing_note explaining UETR recovery,' which goes beyond the schema to reveal valuable output behavior.

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?

Although longer than average, the description is well-structured with clear sections for overview, coverage, field questions, args, and examples. The first sentence front-loads the core purpose, and every section adds substantive value without 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 single optional parameter and the presence of an output schema, the description is comprehensive. It explains the tool's scope, usage, parameter behavior, and a special output detail, making it fully sufficient for selection and invocation.

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 schema's message_type has zero description coverage, but the Args section fully compensates with examples, case-insensitivity note, and the omit-to-list behavior. This provides the agent with complete semantic understanding of the parameter.

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 opens with 'Look up SWIFT message types — MT (FIN) and MX (ISO 20022),' which clearly identifies the action and resource. It also distinguishes itself from siblings by explicitly covering message types and payment field locations, making the tool's unique purpose evident.

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 clear usage guidance: 'Pass a specific type to get full details, or omit to list all types' and 'Also use this tool to answer questions about where specific payment fields live.' However, it does not mention when-not-to-use or name alternative tools, so it lacks explicit exclusions.

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