Get custom field definition

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 safety and idempotency profile is fully covered without the description. The description adds only the single-record scoping, not return shape, error behavior, or permission requirements.

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?

A single nine-word sentence with the resource and lookup key front-loaded and zero filler. Nothing to trim.

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 one-parameter, read-only, annotation-rich getter, the description covers what is needed to invoke it; the absence of an output schema means return values are undescribed, but that is the only remaining gap and it is minor for this tool class.

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 description coverage is 100% with one documented parameter ('Custom field definition ID') including a UUID pattern, so the schema carries full parameter meaning. The description only restates 'by ID' and adds no format or lookup semantics beyond it.

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 (custom field definition), and the word 'single' plus 'by ID' distinguishes it from the sibling list_custom_field_definitions. It stops short of naming that sibling explicitly, so sibling differentiation is only implicit.

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?

'by ID' implies the usage condition (you already hold the identifier), which is adequate but never states when to prefer this over list_custom_field_definitions or what to do if the ID is unknown. No prerequisites or exclusions are given.

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