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

Annotations already cover idempotency and non-destructiveness, and the description adds meaningful behavioral context beyond them: it clarifies that the read mode writes nothing, that setting a brand only affects reply drafts, that nothing polled is changed, no search is started, and no credits are charged. No contradiction with annotations.

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?

Three sentences, front-loaded with the core purpose and the condition for use, followed by a compact call sequence and side-effect notes. Every sentence earns its place; no filler or repetition.

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 two-parameter tool with rich schema descriptions and no output schema, the description covers the full operation modes, side effects, and prerequisite id source. An agent can correctly choose and invoke the tool without unresolved 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 100%, and the schema already explains the absent/id/null behaviors precisely. The description reinforces the same semantics in prose but does not add new parameter-level meaning beyond the schema, so baseline 3 is appropriate.

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 operation pair ('Read or choose') and a specific resource ('the brand a keyword's reply drafts speak for'), with a clear condition ('when the account has several'). This distinguishes it from broader keyword-update or management siblings without needing to open the schema.

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 description gives explicit calling guidance: call without brandProfileId to inspect brands and the current choice, then call with a brand id or null. It also states the appropriate context ('when the account has several'). It does not explicitly name sibling alternatives or exclusions, so it stops short of a full when-not map.

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