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 and openWorldHint=false, so the description's 'pure, read-only, and idempotent' line largely restates structured data. It adds only the modest 'deterministic field dictionary lookup' framing, which is minor context rather than new behavioral disclosure.

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?

Front-loaded one-line summary followed by labeled sections that scan quickly, and every section maps to a real decision the caller makes. The 'Behavioral transparency' block is somewhat redundant against the annotations, which slightly dilutes the otherwise tight structure.

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?

Covers purpose, prerequisites, exclusions, and example return content, and an output schema exists so return-value detail is not the description's burden. Complete enough to call correctly, with only the annotation-repeating section adding noise rather than gaps.

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% for the single message_type parameter, and the schema already supplies the format example and the list_message_types pointer. The description adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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?

States a specific verb (get) and resource (required schema fields) scoped to ISO 20022 E&I message types, and names the sibling tools (generate_message, list_message_types) that bound its role. An agent can distinguish it from list_message_types or generate_message without opening any schema.

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?

Explicitly enumerates when to use it (preparing payloads before generate_message, validating completeness before XML serialization) and when NOT to use it, pointing to list_message_types for discovering supported types. This is a full when/when-not/alternative routing statement.

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