Set a phone number as the primary phone for an account, so the correct number is used for verification and account communication.
Set a phone number as the primary phone for the account.
ACCESS: needs a Proof account. Set PROOF_API_KEY and restart this server, or sign in with start_login — a session opens this tool — then call this tool again.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Phone record ID to set as primary |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false and destructiveHint=true, so the mutation safety profile is covered. The description adds genuinely useful context beyond that: the tool requires an authenticated Proof account and a valid session/API key, including the exact remediation steps. It does not disclose what happens to the previously-primary phone.
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?
Two sentences, purpose front-loaded before the access note, with no filler. The access instructions are somewhat verbose but each sentence earns its place by giving the agent an actionable recovery path.
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-parameter mutation tool with annotations covering the destructive hint and full schema coverage, the description supplies the missing piece (auth requirements). It stops short of explaining side effects on the prior primary phone or any prerequisite that the phone be verified, but is otherwise sufficient.
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% for the single 'id' parameter ('Phone record ID to set as primary'), so the schema carries the meaning. The description adds no additional syntax or format guidance for the id, making the baseline 3 appropriate.
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: 'Set a phone number as the primary phone for the account.' This clearly distinguishes it from the sibling list_phones, remove_phone, and start_add_phone, though it does not name those alternatives explicitly.
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?
Provides strong prerequisite guidance (needs a Proof account, set PROOF_API_KEY or sign in via start_login), but offers no when-to-use-vs-alternatives reasoning, such as when to prefer set_primary_phone over remove_phone or start_add_phone. Usage context is implied by the auth flow rather than explained.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.