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

Annotations only declare the safety profile (readOnly=false, destructive=false, openWorld=true). The description goes well beyond by disclosing rate limits, deliverability thresholds, the confirmation default, the external-recipient warning, and an auth requirement — all actionable behavioral traits.

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?

Purpose is front-loaded and nearly every sentence carries operational value (limits, confirmation, auth). It runs somewhat long and packs multiple constraints densely, but there is little 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?

For an outbound send tool with no output schema, the description covers the key concerns an agent needs: purpose, recipients, limits, confirmation, and credentials. Failure modes or return semantics are not addressed, but that is a minor gap.

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 subject, retailer_ids, body_markdown, and include_faire_direct_link. The description adds nothing parameter-specific (e.g., formatting rules or sourcing for retailer_ids), so the baseline 3 applies.

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 ('Send an email campaign to chosen retailers through Faire Campaigns') and clarifies the mechanism (Faire's Campaigns tool). An agent can distinguish this from read-oriented siblings like faire_list_customers or faire_get_conversation.

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?

Provides concrete usage context: per-retailer weekly caps, the 1/day campaign limit, bounce/spam thresholds, and the default per-call confirmation. It does not explicitly name an alternative tool, but it does specify preconditions (API key with app access) and a strong when-to-use condition ('confirm with the user before each call').

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