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

Annotations already declare readOnlyHint and non-destructive, and the description adds substantial behavioral detail beyond that: daily row shape, metric names, ISO 8601 date format, default 7-day window, and a 404 pilot-enrollment caveat. There is no contradiction between description and annotations.

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?

Five sentences, each carrying distinct useful information: purpose, sequencing, defaults, return shape, date format, and 404 behavior. The core action and prerequisite are front-loaded, with no filler.

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 correctly takes on the burden of explaining return values and error cases: it lists the metrics, specifies the timestamp format, documents the default date range, and provides a fallback diagnostic tool for 404s. This is fully complete for a read-only insights tool with fully documented parameters.

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 defaults, the provider enum, and campaignId provenance. The description restates the list-first requirement and date defaults, but adds little parameter-specific meaning beyond what the schema provides. The baseline of 3 is appropriate.

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 'Get daily performance metrics for a specific paid campaign,' a specific verb+resource statement. The qualifiers 'paid' and 'daily' plus the listed metrics distinguish it from the many sibling campaign-analytics tools. The specificity makes the tool's scope immediately obvious.

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 usage context: call nevent_list_paid_campaigns first to get a valid campaignId, and it routs a 404 to nevent_paid_ads_healthe. However, it never explicitly contrasts with sibling insights tools such as nevent_get_campaign_insights or gives a when-not-to-use condition.

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