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

Beyond the annotations (destructiveHint=true, readOnlyHint=false), the description discloses meaningful behavioral context: writes land in a shared workspace visible and editable by other callers, there is no per-caller isolation, and duplicate contacts are not rejected. This is exactly the kind of side-effect information an agent needs.

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, each earning its place: the core definition, the duplicate-avoidance guidance, and the shared-workspace side effect. The most important information is front-loaded, and there is 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?

For a create operation with 17 parameters, a rich output schema, and shared-workspace side effects, the description covers what an agent needs to call it safely: what it does, what to check first, what side effects to expect, and which sibling to use for non-mutating 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 description coverage is 100%, so the baseline is 3. The description adds no parameter-specific syntax or format details, though its duplicate-rejection warning lightly informs email/identity-related parameters. The schema itself carries the parameter meaning.

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 a specific verb and resource: 'Create a contact — a person saved into this workspace.' It clearly distinguishes itself from search and match siblings by naming post_apollo_contacts_search and post_apollo_people_match and explaining what each is used for instead.

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 gives explicit when-to-use guidance: search first to avoid duplicates, since Apollo does not reject duplicate contacts, and use post_apollo_people_match when the goal is to look someone up without saving. This leaves no ambiguity about which sibling to choose.

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