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

With no annotations, the description carries the full burden. It does disclose two real behavioral traits: the operation is free (0 credits) and the output is a pre-aggregated summary rather than raw records. It does not say whether the result is a read-only snapshot, what period the stats cover, or what is returned for an empty campaign.

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?

One dense sentence front-loads the purpose and enumerates the returned metrics, followed by a short cost note. Every clause carries information; nothing is redundant with the title.

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?

There is no output schema, so the description must describe the return shape — and it does, naming the specific metrics and the two breakdown dimensions. The notable gap is the time window / scope of the stats, which an agent would need in order to interpret or compare results.

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% for the single required campaign_id parameter, so the schema already documents it. The description adds the qualifier 'Constellation campaign', clarifying the ID's domain, which is a modest but real contribution over the schema's bare 'Campaign id'.

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-and-resource ('Summary stats for a Constellation campaign') and enumerates exactly which metrics come back: target count, entry count, outreach volume, acceptance/reply rates, broken down by pool and composite-score tier. This is far more specific than the sibling list's other 'get_*' insight tools, though it never names a sibling it competes with.

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?

Usage is implied by 'summary stats for a campaign' — an agent can infer this is the overview tool — but there is no explicit when-to-use/when-not clause and no routing to alternatives such as get_engagement_trends or get_cost_estimate. The 'Free — costs 0 credits' note nudges cost-based decisions but is not genuine usage guidance.

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