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

Annotations provide readOnlyHint=true and openWorldHint=false, but the description adds meaningful behavior: 'Free, and it never scrapes — safe to call at the start of every session.' It also discloses the default time window (last 24 hours) and the incremental behavior via `since`. No contradiction with annotations.

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 tight sentences: purpose first, then safety/usability, then usage pattern. Every sentence earns its place with no fluff. The most critical info (incremental cursor) is front-loaded with `since`. Perfectly structured for quick agent scanning.

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 3-param tool with no output schema, the description gives a clear overview of return content (posts, replies, links, engagement), usage scope (across chats), and a pointer to the cumulative sibling. Combined with readOnlyHint, an agent has everything needed to call it correctly and integrate it into a multi-step workflow.

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 covers 2 of 3 parameters (67%), but the description enriches `since` significantly by tying it to the previous call's `checked_at` and explaining omit behavior. The missing campaign_id is self-evident. Since the description compensates for the gap and adds real semantic depth, it earns a 5.

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: 'Catch up on a campaign since the last check' and enumerates the exact return content (posts, replies, LIVE links, engagement). It clearly distinguishes from siblings like get_campaign_results by naming it explicitly for cumulative data, making purpose unambiguous.

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?

Explicitly says to use this to resume a standing growth operation across chats, then get_campaign_results for the cumulative picture. Also advises calling at the start of every session and explains how to use `since` for incremental checks. Clear when/why and points to an alternative.

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