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

Annotations already cover the read-only/idempotent safety profile, and the description adds genuinely non-obvious behavior: the upstream field cannot return PENDING or FAILED rows at all, and failures are only visible via lead_get. It also warns that the status parameter filters the lead's pipeline status rather than the activity's, preventing a very plausible misuse.

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: what it returns, what it cannot return, and the disambiguation warning. The scope constraint is front-loaded and no sentence 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?

With no output schema, the description supplies the shape ('one row per lead per step') and the completeness limitation (no pending/failed rows), which is the critical information. It stops short of describing pagination/ordering or the default range window, but nothing essential for calling it correctly is missing.

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 page, range and its date aliases, keyword, and the status enum. The description's status clarification is valuable but duplicates what the schema field description already states, and it says nothing about range/pagination semantics beyond what is structured.

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 resource (completed activities) and even the row grain ('one row per lead per step'), with an explicit scope constraint that only COMPLETED rows are returned. It does not name sibling listing tools like campaign_activity_summary or activity_skip, so differentiation is partially inferred rather than stated.

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?

Gives an explicit routing rule — use lead_get to inspect a failure and its failedReason — which is exactly the kind of alternative-selection guidance agents need. It lacks a 'when not to use' condition for aggregate/analytics siblings, so it is clear but not exhaustive.

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