Custom Field Capabilities List

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description still adds real context the annotations do not carry: the endpoint is marked unstable, the API version is unstable, and the required scopes are stated, which matters for an agent deciding whether to depend on it.

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 purpose is front-loaded in the first line, followed by endpoint, scope, and version — a tight, scannable shape with no filler. Minor redundancy: instability is signalled twice, in '(unstable API)' and 'API version: unstable'.

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 read-only, fully-described 4-parameter lookup with no output schema, the description covers what an agent needs to invoke it correctly. It stops short of describing what a 'capability' looks like in the response, which is the one substantive gap given no output schema exists.

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%, so all four parameters are already documented, including both enums; the baseline of 3 applies. The HTTP path template does clarify that entity/namespace/slug compose the definition identifier, but that is marginal value beyond the schema's own 'Definition namespace/slug' descriptions, and response_format is never discussed.

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 and resource: list the capabilities of a custom field definition, identified by entity/namespace/slug. That clearly separates it from the mutating siblings (custom_field_capabilities_add/remove) and from custom_field_defs_get, though it never names an alternative explicitly.

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?

Usage is only implied — an agent must infer it should call this before adding or removing capabilities, or to introspect what a definition supports. The required OAuth scope (read_products/write_products) is a useful prerequisite, but there is no explicit when-to-use or when-not-to-use guidance.

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