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

Annotations already mark this as destructive and not idempotent, but the description adds critical behavioral context beyond that: partial success is normal, responses must be evaluated per record, and writes land in a shared AIsa workspace visible/editable by other callers with no isolation. These are exactly the kind of non-obvious traits an agent needs to know.

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 compact, front-loaded with the core purpose, and every sentence earns its place: bulk behavior, per-record success handling, and shared-workspace side effects. There is no redundant or distracting wording.

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 a full output schema and 100% schema coverage, the description need not explain return values or parameter formats. It supplies the essential usage caveats for a destructive bulk mutation tool, though it could have been slightly stronger by explicitly naming the singular create sibling as the alternative for one-off creation.

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 parameters like run_dedupe and append_label_names are already documented. The description adds no additional parameter-level meaning beyond restating the bulk nature, so the baseline 3 baseline 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?

The description clearly states the verb ('Create') and resource ('several contacts in one call'), making the bulk nature obvious. It is distinguishable from the singular post_apollo_contacts sibling by the explicit 'several contacts in one call' phrasing, though it does not name that sibling directly.

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?

The description implies usage for bulk contact creation but does not explicitly state when to prefer this tool versus alternatives like post_apollo_contacts. It does provide important operational guidance: partial success is expected and responses must be read per record, plus the shared-workspace warning that affects whether this tool is appropriate in a given context.

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