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

Annotations already indicate non-read-only, non-destructive, open-world hints. The description adds valuable context beyond those: the model may return a best fit or a no-selection result, and there is a cost of 4 MESH/call. This adds useful behavioral detail without contradicting 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 concise sentences front-load the core purpose, then cover inputs/output behavior, and finish with a usage caveat and cost. No filler or redundant restatement; every sentence earns its place.

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?

With no output schema, the description adequately explains the return possibilities ('best fit or no-selection') and the inputs. Combined with the usage constraint and cost, it provides enough context for an agent to call it correctly, though it omits edge-case details like error handling.

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%, so the schema already documents profile, content, and goal thoroughly. The description merely restates these names ('Send profile, candidate content options, and a goal') without adding any new semantics, earning the baseline score.

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 uses a specific verb and resource: 'Choose which concrete content option to show a specific user and how to frame it.' It clearly distinguishes this tool from generation tools by stating it ranks existing variants rather than inventing a campaign, making its role unmistakable.

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 when-to-use ('Use it to rank existing variants') and when-not-to-use ('not to invent a whole campaign from scratch'). It also specifies the required three inputs, making invocation conditions clear.

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