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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered; the description adds information the annotations cannot express: the read is free (no analysis credits consumed), it is plan-gated to Indie/Agency, and it returns `analysis: null` rather than erroring when no analysis exists. That null-vs-error distinction is the key behavioral fact for correct agent handling.

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 return payload, followed by short clauses for the fallback, cost and plan gate. Slightly awkward mid-sentence dash construction for the sibling routing, but no sentence is wasted.

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 still enumerates what comes back (analysis fields plus video transcript) and covers the null case, cost, and plan prerequisite. Nothing an agent needs in order to call this correctly and interpret the result is missing.

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 `creative_id` field already spells out that it is the Sonar id from sonar_ad_spy_ads, not the Meta `ad_id`. The description adds nothing about the parameter, so the baseline 3 applies — the schema carries the full parameter burden.

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 resource and scope: the cached AI analysis of an ad (hook, angle, format, structure, CTA, why it works) plus its video transcript, and explicitly names the empty case (`analysis: null`). It also names the sibling sonar_ad_spy_analyze_ad as the counterpart, so an agent can separate the cached read from the analysis-generating tool without opening either schema.

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?

Gives an explicit routing rule: if the result is null / not yet analyzed, call sonar_ad_spy_analyze_ad instead. It also states the access condition (Indie or Agency plan, trial counts) and that the call is free, which are the two conditions an agent needs before choosing this tool.

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