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

Annotations already declare this a safe, idempotent read, so the description correctly spends its words elsewhere: it discloses that this tool returns the full activity history and campaign-flow position, and that FAILED rows with `failedReason` are visible here only because activity_list returns COMPLETED rows. That is non-obvious behavioral context an agent could not infer from any structured field.

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, front-loaded with the primary payload and then the routing constraints. The 'single call to make when asked...' clause is followed by two concrete alternatives that each carry distinct information; nothing is redundant.

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 still tells the agent what comes back (profile, activity history, campaign position, failedReason) and how it differs from the cheaper list calls. Nothing needed to invoke or interpret the call 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 leadId, includeMessages, and includeActivities are already documented. The description adds nothing about the optional flags (e.g. that includeMessages is the heavy one to avoid), so baseline 3 applies.

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+resource ('Full profile for one lead') and enumerates the payload: profile, complete activity history, and current campaign position. It explicitly separates itself from two siblings (activity_list, lead_list), so an agent can choose it without opening any schema.

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 a concrete trigger phrase ('when asked "what happened with this person"') plus two negative exclusions: it is the only source for FAILED actions, and lead_list should not be paged to reconstruct history. When-to-use, when-not-to-use, and alternatives are all present.

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