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

Annotations already declare it is a non-readonly, non-destructive, non-idempotent, non-open-world mutation. The description adds genuinely useful context beyond that: AES-256-GCM secret storage, server-to-server routing, agents never seeing URL/token, and the active-account routing requirement. It stops short of describing failure modes or rate limits, so not a full 5.

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?

Four front-loaded sentences with little waste, leading with the core action and security guarantee. The '(Mode B)' fragment is dangling jargon, but otherwise the structure is tight.

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?

An output schema exists, so return values need not be explained, and the description covers the security model and account prerequisite. However, for a 16-parameter mutation with only 25% schema coverage, it omits guidance on most parameters and any failure/validation behavior, leaving notable 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 description coverage is only 25% across 16 parameters, so the description carries a large burden, yet it only adds meaning for one field (price_per_call_usd_cents). Enums, auth_method, secret, pricing_model, request_template, and the many other params are left undocumented by the description.

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?

The description names a specific verb+resource ('Register a proxy endpoint') and clarifies it is for sellers registering endpoints, distinguishing it from siblings like seller_list_my_endpoints and seller_publish_document. The parenthetical '(Mode B)' is unexplained jargon that adds no discriminating meaning for an agent.

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?

It states a prerequisite ('Account must be status=\'active\'') which gives conditional context, but it never says when to choose this over alternatives or names any sibling. Usage is largely implied rather than explicit.

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