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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuine context the annotations cannot: it enumerates the returned statistics, states freshness ('latest daily'), the normalization basis (per 1,000), and the panel-count inclusion — all without an output schema to lean on.

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?

A single dense sentence that front-loads the resource and freshness, then lists the metrics and the optional filter. No filler; 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?

With no output schema, the description competently explains return contents (median, quartiles, extremes, panel counts) and recency. Minor gaps remain — currency/unit normalization for 'per 1,000' and whether aggregation is per service — but an agent can call it correctly.

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 single parameter's description already says 'Platform slug, e.g. "youtube". Omit for all.' The description only echoes this with 'Optionally one platform only', adding no format or scope detail beyond the schema. Baseline 3 for a fully documented schema.

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+resource and enumerates the returned metrics (median, quartiles, cheapest/dearest per 1,000, panel count) plus 'latest daily', so an agent knows exactly what this returns. It does not, however, distinguish itself from siblings like compare_service_prices or market_stats, which likely overlap.

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?

'Optionally one platform only' implies the filtering use case, but there is no explicit when-to-use, when-not-to-use, or routing to compare_service_prices / market_stats for cross-service comparison. Usage is only inferable.

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