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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description adds genuinely behavioral context beyond them: sendMode is IMMUTABLE after creation, Pro-only gating for AI/follow-ups/InMail, and that enabling follow-ups without Pro errors. It does not describe permissions, rate-limit behavior, or response shape beyond the ID, so it is strong but not exhaustive.

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 purpose and return value are front-loaded, then the mode taxonomy, and every sentence carries real content. It is a dense single block that repeats some sendMode/Pro-only detail already present in the schema, so there is minor redundancy, but nothing is 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 a 17-parameter tool with nested objects and no output schema, the description covers the two main creation flows, their gating rules, and the return value ('campaign ID'). It does not enumerate parameter defaults or the full follow-up structure, but the schema descriptions carry those, so coverage is adequate.

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 baseline is 3, but the description adds cross-parameter logic the schema states only locally: campaignType determines which parameters matter, AI mode makes messageTemplate/inMailSubject optional, and promptId is ignored for outreach. That relational guidance raises it above baseline.

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 a specific verb+resource ('Create a new campaign in LinkedNav') and states the return value ('Returns the campaign ID'). It then distinguishes the two campaign types and routes the agent to the correct add-leads sibling for each (add_lead_to_campaign vs add_message_targets), so it is separable from create_comment_campaign, duplicate_campaign and other siblings.

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 clearly explains when each campaignType applies ('outreach' vs 'message'), the two message send modes, and that AI mode/follow-ups/InMail are Pro-only, giving strong selection context. It stops short of naming explicit alternatives to avoid (e.g. duplicate_campaign, create_comment_campaign) or stating when not to use this tool.

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