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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds the context that the visitor ID comes from the _fs_vid cookie and that the result includes a merged activity timeline, but it does not go beyond that to cover auth requirements, failure behavior, or other operational traits.

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 sentences carry substantial information without waste. The first sentence front-loads the complete list of profile components, and the second sentence states the required input source. Every clause contributes value.

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 a read-only annotation, an existing output schema, and full parameter documentation, the description is sufficient for an agent to select and call the tool correctly. It explains the key prerequisite (the cookie-derived visitor ID) and clearly conveys the tool's scope without needing to restate return format or schema details.

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 all three parameters are already documented in the input schema. The description repeats the cookie-source detail for visitorId but adds no new parameter-level meaning beyond what the schema provides.

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 'Get' with a clear resource ('full visitor profile') and enumerates the profile contents: identity, traffic source, activity, revenue, identified profile, and merged timeline. This distinguishes it from sibling analytics tools that focus on a single dimension such as get_browers or get_goals.

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 clearly establishes when to use the tool: when a caller has a visitor ID and needs the complete cross-dimension profile of one visitor. It does not explicitly name alternatives or when-not conditions, but the context and title make the intended use obvious relative to the sibling analytics tools.

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