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

Adds real context beyond the annotations: no lookup credit is consumed, a nonexistent list name creates the list, and the operation does not push anything into the CRM. Annotations already declare idempotent/non-destructive/closed-world, so the residual gap (error behavior on invalid or stale profile_url) is minor.

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 compact sentences, front-loaded with the core action and cap, then credit/creation semantics, then the scope boundary. No 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?

Given an output schema and full annotation coverage, the description supplies everything an agent needs to choose it and call it correctly: prerequisites on input provenance, list-creation side effect, cost implications, and the list-vs-CRM distinction.

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% and each parameter carries its own description, so the schema does the heavy lifting. The description mostly restates schema facts (100-item cap, auto-creation of list_name) rather than adding syntax or precedence rules such as what happens if both list_id and list_name are supplied.

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?

Specific verb (save) plus resource (people → a list), with quantity bound (up to 100) and the required source of the items (profile_url from search_prospects or find_contact_details). The final sentence explicitly separates it from the CRM siblings: 'it does not add them to the CRM.'

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?

Clear when-to-use context: only people returned by search_prospects/find_contact_details, and only when the goal is a list for later rather than a CRM write. It stops short of covering the list_id vs list_name choice or pointing to list_lists as the way to obtain list_id, which the schema does instead.

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