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start_2fa_for_action

Initiate a two-factor authentication challenge to authorize sensitive actions like API key management or account changes. Use it when a 403 2fa_required error occurs to obtain a grant for the protected operation.

Instructions

Start a 2FA challenge that grants the authenticated user permission to perform a sensitive action. The 2FA must complete on a channel DIFFERENT from the user's last login channel (the backend enforces this). On success a grant is stored keyed by the user id and action_type; middleware on the protected endpoint reads the grant and allows the mutation.

Destructive action types (api_key_create, api_key_revoke, api_key_regenerate, api_key_view, account_delete, phone_remove, email_remove, revocation_bulk) are capped at 5min TTL and forced single-use by server policy. Configuration scopes (settings_write, profile_update, templates_write) allow up to 24h TTL and caller-chosen single_use — useful for agents making multiple settings mutations in one session.

Agent usage: (1) Attempt the sensitive call; if you get 403 2fa_required note the action_type. (2) Call start_2fa_for_action with that action_type and a channel different from the login channel. (3) Present the challenge: on telegram/whatsapp pass deep_link to render_auth_link; on sms show sms_message and the number to send it to; on email check the response first: with more than one verified email and no email_id given, it answers 200 with requires_email_selection: true and available_emails — NO session was started and nothing was sent, so ask the user which address and call again with email_id rather than telling them to open a mailbox. Never hand qr_text to a link renderer — it is the link already rendered as QR art. Print it verbatim inside a fenced code block only when a real terminal needs the QR. (4) Call wait_for_2fa until the session is verified. (5) Retry the original sensitive call.

ACCESS: needs a Proof account. Set PROOF_API_KEY and restart this server, then call this tool again. start_login does NOT open this tool.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
channelYesChannel for the 2FA challenge — must differ from the user's last login channel
email_idNoOptional: specific UserEmail id for email-channel 2FA
phone_idNoOptional: specific UserPhone id for phone-channel 2FA
single_useNoWhether the grant is consumed on first use. Server forces true for destructive action types. Defaults to true.
action_typeYesThe sensitive action the 2FA grant will authorize. Destructive scopes (api_key_*, account_delete, phone_remove, email_remove, revocation_bulk) are capped at 5 min TTL + forced single-use. Configuration scopes (settings_write, profile_update, templates_write) allow up to 24h TTL with caller-chosen single_use. See config/twoFAPolicy.ts on the backend for the canonical policy.
ttl_secondsNoRequested grant lifetime in seconds. Server caps to 300s for destructive action types, 86400s for configuration scopes. Defaults to 300 if omitted.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. First observedv1.1.0

TDQS

A5/5.0
Behavior5/5

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

With no annotations, the description carries the full burden, and it delivers: the backend enforces a different channel than the login channel, TTL caps and forced single-use differ by action type, the email flow can return a no-session-started selection state, and qr_text must not be passed to a link renderer. These are exactly the non-obvious behavioral traits an agent needs to invoke the tool correctly.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long but every sentence carries operational value: policy constraints, channel-specific rendering rules, an email edge case, and a numbered agent workflow. It is structured from core purpose to policy to actionable steps, with no filler or repetition of schema content.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This tool has no output schema and no annotations, yet the description covers the critical response behaviors: deep_link, sms_message, requires_email_selection, available_emails, and qr_text handling. It also explains the grant/TTL mechanics and names the related downstream tools (wait_for_2fa, render_auth_link), making it fully actionable for a complex multi-step flow.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Although schema coverage is 100%, the description adds substantial meaning beyond the field docs: it explains when single_use is forced vs caller-chosen, how ttl_seconds is capped per scope and defaults, and why channel must differ from the login channel. It also connects email_id and the requires_email_selection response state, which the schema alone does not convey.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

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: 'Start a 2FA challenge that grants the authenticated user permission to perform a sensitive action.' It further clarifies the mechanism (grant keyed by user id and action_type, read by middleware), making the tool's unique role unmistakable and distinguishing it from generic 2FA tools like start_2fa or verify_2fa.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides an explicit 5-step agent workflow: attempt the sensitive call, handle 403 2fa_required, call this tool with the correct action_type and channel, present the challenge per channel, wait for verification, then retry. It also gives exclusions ('start_login does NOT open this tool') and handles an edge case where email selection requires a second call instead of telling the user to check their mailbox.

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

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