Media kit data

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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: a stable versioned output contract (schema_version 1, snake_case, *_pct 0-100, *_s seconds) and, importantly, graceful degradation where unsupported YouTube metrics return null and are explained in `unavailable` instead of erroring. It stops short of 5 by saying nothing about cost/latency of this large aggregate call or any auth requirements.

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, front-loaded with the tool's purpose and followed immediately by the output contract and null-handling rule. The long enumeration of sections is dense but each item earns its place by telling the agent what it will receive; minor cost is that the section list reads as a run-on.

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 nine optional parameters, full schema coverage, annotations, and an output schema, the description is nearly complete: it explains the content of the return value and the null/`unavailable` behavior that an agent most needs to interpret results. It omits any note about authentication prerequisites or the size/latency tradeoff of requesting a full snapshot.

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 all nine parameters in detail (period semantics, date overrides, trend_months, top_countries, include_revenue, min_upload_age_days). The description adds only the implicit notion of "vs previous period" and does not clarify parameter interactions such as start_date overriding period beyond what the schema states, so the baseline 3 applies.

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 concretely enumerates what the snapshot contains (channel profile, period performance vs previous period, Shorts vs long-form, impressions funnel, trends, audience demographics, uploads, top videos, traffic sources), which lets an agent recognize it as a bundled aggregate rather than a single-metric tool. It falls short of 5 because it never explicitly contrasts itself with the granular siblings (get_audience_breakdown, get_impressions, get_traffic_sources) by name, leaving the bundling relationship implicit.

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?

"Everything a creator media kit / sponsor deck needs" gives a clear, concrete use context that tells the agent when this tool is the right choice. There is no explicit when-not guidance (e.g., that single-metric siblings are cheaper if only one section is needed) and no stated prerequisites such as authentication or required scopes.

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