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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so 'Limitations: read-only' merely restates what structured data provides. No additional behavioral context (e.g. behavior on a missing ID, auth requirements across the six credential params) is disclosed.

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?

Two short, front-loaded sentences with no filler. It is efficiently sized for a simple getter, though 'Limitations: read-only' adds little given the annotations.

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 simple single-resource getter with no output schema and an adequately described input schema, the description is minimally sufficient. It omits any note about the returned definition shape or not-found behavior, which keep it at the baseline rather than above it.

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 83%, so the schema already documents the parameters well. The description adds only the endpoint path and does not clarify which credential parameter is preferred or what custom_field_id must reference, so this is the standard baseline.

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+resource ('Gets a custom field definition') and even names the REST path, which clearly distinguishes it from list_custom_fields, create_custom_field, and update_custom_field. It stops short of explicitly differentiating from its siblings, but the single-fetch semantics are unambiguous.

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 'read-only' limitation implies a safe retrieval use, but there is no explicit when-to-use guidance and no pointer to alternatives such as list_custom_fields for enumeration. Usage is only implied by the verb.

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