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

Annotations mark it as a non-read, non-destructive write; the description adds real behavioral context beyond that — that this is a security allowlist setting and that a leaked API key cannot bypass it. It does not state what happens on duplicates, required permissions, or the response shape, leaving a modest gap.

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 with the action and scope, then rationale, then format rules, then the user-confirmation step. Four sentences with little waste, though the security-rationale sentence is more context than strictly necessary.

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 2-param registration mutation with no output schema and annotations already covering the safety profile, the description covers purpose, format, and prerequisites. Missing only edge-case behavior (duplicate origin handling) and any auth notes.

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 baseline is 3, but the description goes further by specifying the exact origin format (scheme+host only, https or localhost http, no wildcards, no path), which the schema's terse 'e.g. https://acme.com' does not fully convey. The label parameter is left to the schema.

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 (register/allow) and resource (one website framing the account's checkout), which an agent can distinguish from the sibling list/remove embed-origin tools by inference. It does not explicitly name those alternatives, so it falls just short of full sibling differentiation.

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?

Gives concrete operating context ('only registered origins can ever frame the checkout') and an explicit behavioral instruction ('Confirm the exact origin with the user first'). It stops short of naming the alternatives (swop_list_embed_origins, swop_remove_embed_origin) that would make routing unambiguous.

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