Add contacts to a contact list in bulk, up to 5000 per request, using phone numbers and optional name fields.
Add contacts to a contact list (up to 5000 per call). Body: contacts[] with phone_number each.
| Name | Required | Description | Default |
|---|---|---|---|
| uuid | Yes | Contact list UUID | |
| contacts | Yes | Contacts to add (max 5000) |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It mentions the 5000 limit but omits side effects (e.g., duplication handling, idempotency, error behavior, whether the list must pre-exist). This is a mutation tool with no disclosure of consequences.
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?
A single, front-loaded sentence that captures purpose and a key constraint. No wasted words, easy to parse.
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 no annotations or output schema, the description is functional but thin. It covers the core action and limit but lacks guidance on prerequisites, failure modes, or what the response contains. An agent would have to infer behavioral details.
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 the description's 'contacts[] with phone_number each' simply mirrors the schema. The only addition is the 5000 limit, which the schema already states in the contacts property description. No extra meaning is added.
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 and resource: 'Add contacts to a contact list'. Clearly distinguishes from siblings like create_contact or create_contact_list. The limit 'up to 5000 per call' adds a precise scope.
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 the tool is for populating an existing list but does not explicitly say when to use it over alternatives like create_contact or update_contact_list. No when-not-to-use conditions or alternative references are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.