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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description reinforces 'Read-only.' It adds many behaviors beyond annotations: ordering ('newest first'), capping and truncation ('Goals and clicks are capped separately by limit; goalsTruncated/clicksTruncated say when older events exist'), event scope ('typed replies, commands and website visits never appear'), error handling ('An unparsable value is rejected, never ignored'), and permission requirements ('Requires the view_logs permission'). This is rich behavioral context that goes well beyond the annotation metadata.

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 dense but every sentence earns its place. It front-loads the core purpose, then adds the sibling distinction, event scope, capping/truncation details, and a required prerequisite. No filler or repetition—each clause contributes to correct usage.

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?

Despite lacking an output schema, the description conveys what the tool returns (goals, clicks, and optionally flowRuns) and how to interpret truncation flags. It covers prerequisites, error cases (MCP_APPLICATION_REQUIRED), permission requirements, and value formats. An agent has everything needed to call it correctly without further lookups.

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 coverage is 100%, so parameters are already documented. The description adds meaning that the schema does not: it clarifies what 'clicks' means ('inline/menu button presses inside the bot'), explains the independent caps per stream tied to limit, and notes the permission requirement for includeFlowRuns. This adds valuable context beyond the schema's field descriptions, though it does not enumerate each parameter.

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 the exact resource and action: 'Return one contact's engagement history: goals they achieved and buttons they clicked, newest first, plus all-time goal totals.' It explicitly distinguishes itself as the per-contact companion to get_broadcast_analytics (which is aggregate), making its purpose immediately clear and differentiating it from the obvious sibling.

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 names the alternative (get_broadcast_analytics) and explains when to choose each: 'per-contact companion to get_broadcast_analytics (which is aggregate)'. It also provides a prerequisite: 'Call list_contacts first to find the contactId.' and clarifies the scope of what counts as clicks. This is explicit when-to-use guidance with exclusions.

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