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

Beyond the readOnly/idempotent annotations, the description adds non-obvious behavior: results are chronological oldest first, each daily pull has a 30-day window, and the default is the most recent 90 pulls. It also discloses the scope prerequisite and the filtering options, which meaningfully helps an agent predict behavior.

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?

Three sentences with no filler: the first states what the tool returns, the second provides parameter sourcing, and the third covers defaults, filtering, and prerequisites. Key behavioral details are front-loaded.

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 carries the burden of explaining the return payload, and it does: contents, ordering, defaults, filters, and required scope are all covered. For a read-only history retrieval tool, nothing essential for correct invocation 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 description coverage is 100%, so the schema already documents campaign_id, since, and limit thoroughly. The description repeats the default of 90 pulls and the since/limit filtering but does not add meaning beyond the schema; the campaign_id provenance is already present in the schema property description.

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 opens with a concrete subject and scope: 'One campaign's pull history as a chronological series.' It specifies the exact contents (30-day window, impressions, clicks, spend, platform, account, objective, status), and it distinguishes this tool from siblings by noting campaign_id comes from get_paid_media.

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?

It gives clear context: this is for a single campaign's history, campaign_id should come from get_paid_media, and the paid_media section must be in scope. It does not explicitly name alternatives or when-not-to-use, but the source relationship and scope precondition provide practical selection guidance.

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