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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuine context beyond them: a plan/entitlement gate that determines whether the call succeeds at all. It does not describe failure behavior when the plan check fails, but the entitlement disclosure is real added value.

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 tightly written sentences with zero padding; the what and the payload come first, the prerequisite second. Every clause carries information.

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 with an output schema, the description covers purpose, payload, and the entitlement prerequisite that an agent could otherwise miss. Only the entitlement-failure behavior and any routing to the search sibling are absent, which is a minor gap.

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% and the schema itself documents company_id as the brand id from sponsor_search_brands, so the single parameter is fully specified structurally. The description adds nothing about the id format or provenance, so baseline 3 applies.

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 ("Return one brand from the Find sponsors directory") and enumerates the payload (description, social URLs, technology list). It contrasts implicitly with search-style siblings via "one brand," though it never names sponsor_search_brands or sponsor_lookup_brand as the alternative it is not.

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 implied: this is the by-id fetch whose id comes from the search tool, and the description adds an entitlement prerequisite (Creator Max / agency Pro, Scale, Enterprise). It gives no explicit when-to-use routing against sponsor_lookup_brand or sponsor_get_contact, which is the main gap.

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