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

Annotations already declare readOnlyHint and idempotentHint, but the description adds substantial behavioral context: the semantics of sentiment null (unscored vs neutral), the structural nature of awaitingOurReply (only sees Onsa-sent messages, hand-made replies invisible), daysSinceLastReply as elapsed days even if answered, looksLikeBroadcast as a floor not verdict, and top-level count spanning the whole campaign with exclusions. This far exceeds the minimal annotation coverage and clarifies subtle data interpretation.

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?

The description is long but every sentence earns its place, explaining nuanced semantics that an agent must understand to interpret results correctly. It is front-loaded with the core purpose, then systematically explains the three derived fields and the top-level count, using clear structure. No fluff or redundancy.

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 an output schema present, the description needn't restate return structure. It covers edge cases (unscored replies, hand-made replies, broadcast detection limits, daysSinceLastReply semantics) and clarifies the meaning of derived fields and the top-level counter. For a read-only tool with rich output semantics, this is complete for correct invocation and interpretation.

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% with both parameters fully documented (limit with default and ordering, campaignId with format). The description adds no new parameter-level semantics beyond what the schema already provides, so the baseline of 3 is appropriate. It does mention the interaction between limit and the top-level count, but that pertains to output behavior rather than parameter usage.

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 clearly states what the tool does: returns reply text paired with the outbound message, and explicitly contrasts with get_campaign_stats which counts replies. The verb 'returns' and resource 'reply text' are specific, and the sibling differentiation is explicit, leaving no ambiguity about purpose.

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?

The description provides direct guidance on when to use this tool versus get_campaign_stats, noting that this returns the words while the sibling counts and labels. It also explains when this tool may return more replies than the funnel counts, clarifying its scope and limitations relative to the alternative.

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