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

The description warns that writes affect all callers in the shared 'AIsa workspace' and lack per-caller isolation, which is critical for a destructive write operation. Annotations already indicate destructiveHint=true, but the description adds specifics about visibility and sharing, going beyond annotations.

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 three sentences, each adding critical value: the operation scope, the partial-update guidance, and the shared-workspace warning. No filler, and the safety warning is front-loaded after the core purpose.

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 single-record update tool with many optional fields, the description covers the essential usage rules (partial update, stage id source, shared workspace) and output schema exists. The warnings about shared state are crucial and complete. Nothing critical 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?

With 100% schema coverageaint but all parameters are simple strings; the description adds meaningful guidance especially for contact_stage_id, noting it expects an id from get_apollo_contact_stages. This clarifies the parameter's expected source, which the schema does not. Given high coverage, the baseline is 3, but the added stage-id guidance justifies a 5.

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 title 'Update a Contact' and description 'Update one contact by its Apollo id' clearly state the specific verb (update), resource (contact), and target identifier (Apollo id). It distinguishes from siblings like post_apollo_contacts (create) and post_apollo_contacts_bulk_update (bulk).

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 instructs to 'Send only the fields you intend to change' and notes the shared workspace side-effect, which clarifies when to use it. It doesn't explicitly mention alternatives for bulk updates or creation, but the sibling names (post_apollo_contacts, post_apollo_contacts_bulk_update) imply such options.

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