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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint, so the baseline bar is lower. The description adds genuinely useful non-annotation context: the requirement that the provider campaign's sequence use {{email_subject}}, {{email_body}}, and optionally {{email_1follow_up_body}} for send_email to work as expected. This is a real-world behavioral prerequisite that annotations cannot express and that prevents a common misconfiguration failure.

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: purpose+returns, downstream usage, and the critical placeholder constraint. The most identifying information is front-loaded, and every sentence earns its place.

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 a simple read-only listing tool with one enum parameter and full safety annotations, this is nearly complete: it covers purpose, provider choice, returned fields, and the send_email integration. The only gap is that the return shape is listed as field names without types or format, but since no output schema exists the parenthetical field list is reasonable compensation.

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 0%, so the description must compensate. It does so implicitly: 'connected Smartlead or Instantly account' maps directly onto the provider enum values, telling the agent which service each value selects. For a single self-documenting enum parameter this is sufficient, though it stops short of an explicit per-value definition.

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 first sentence names a specific verb and resource ('List campaigns in the connected Smartlead or Instantly account') plus the returned fields (id, name, status, active). This clearly separates it from the similarly named sibling list_campaigns by scoping it to external provider accounts, and from list_email_integrations/list_email_outreach which cover different surfaces.

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 gives strong downstream usage guidance: 'Pass the id as provider_campaign_id to send_email' tells the agent exactly how the result is consumed and when this tool matters. It does not explicitly contrast with alternatives like list_campaigns or state when not to use it, but the provider-scoped framing and send_email linkage make the intended call path clear.

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