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

No annotations are provided, so the description carries the full burden. It clearly declares 'Read-only' and 'requires the MCP_API_KEY bearer token', and discloses that breakdown runs 'a second, heavier aggregation' – indicating cost. It does not mention rate limits or error conditions, but the core safety and auth profile is covered.

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?

The description is moderately long but every sentence earns its place: the first sentence states the core data, the second explains breakdown, the third gives usage rationale, and the last covers read-only and auth. It is front-loaded with the primary function and does not include fluff.

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 read-only analytics query, the description covers everything an agent needs: what data is returned, how to adjust breakdown, when to use it, and the required authentication. It does not rely on an output schema (none present) but still communicates the expected return content. Missing details like exact number formatting are minor and unlikely to impair correct invocation.

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 parameters are already documented. The description adds meaningful context: it explains the purpose of breakdown, that period is only for the breakdown window (reinforcing the schema), and why breakdown matters for interpreting traffic. This goes beyond the schema's bare parameter definitions.

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 states a specific verb ('Get') and resource ('visitor analytics for one of the connected account's products'), and enumerates the exact data returned (views, unique visitors for 7/30 days and all time, review counts). It clearly distinguishes itself from siblings like list_product or seo_audit_summary by focusing on visitor analytics, avoiding any ambiguity.

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 guidance: 'ask for the breakdown whenever the question is why traffic moved or which source is working' and explains why breakdown is needed ('Counters alone cannot tell...'). It also states the tool is read-only and account-scoped, establishing boundaries without mentioning alternatives (no close siblings exist).

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