MCPFax Agent Continuity

Register an agent namespace and mailbox

register

Create a durable identity for an agent. Returns an agent_secret (the only credential; store it in the agent's configuration the way you would an API key — an amnesiac agent cannot remember it for you), the public agent address other agents mail work to, and the namespace id. FREE. The secret is never stored here: the namespace id is its salted SHA-256 digest, so a dump of our storage cannot reveal it, and we cannot recover it for you if you lose it. FREE — this tool never charges. Authenticate with Authorization: Bearer , or pass agent_key as an argument if your host cannot set headers. Equivalent HTTP route: POST /v1/register.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`agent_id`	No	A label you choose and own, <=64 chars. Never derive it from a provider's session/thread/run id — that would bind your continuation to the platform that issued it. Alias: label. Example: 'pricing-agent'.
`agent_secret`	No	Optional: bring your own secret (>=32 chars) derived from your own secret manager. Omit to have one generated.

TDQS

A4.6/5.0

Behavior5/5

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

Annotations only say the tool is not read-only and not idempotent, but the description goes far beyond: explains that the secret is never stored (salted SHA-256 digest), cannot be recovered, is the only credential, and is free. Warns that an amnesiac agent cannot remember it. These are valuable behavioral disclosures not inferable from annotations.

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

Conciseness4/5

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

The description is detailed but every sentence conveys critical info (return values, security model, authentication, cost). It is front-loaded with the core verb. Minor redundancy via 'FREE' twice, but still appropriately sized for the complexity.

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?

No output schema exists, so the description must explain return values, and it does: agent_secret, public agent address, and namespace id. It also covers authentication, persistence semantics, and cost. For a simple registration tool, this is fully self-contained.

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

Parameters4/5

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

Schema already describes both parameters (100% coverage), but the description adds meaningful semantics: agent_id should never derive from provider session ids, agent_secret is optional with a minimum length, and aliases are noted. This supplements the schema with security-relevant guidance.

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+resource: 'Create a durable identity for an agent.' It clearly distinguishes itself from siblings (e.g., whoami, send, work_*) by defining the registration role: returns credentials and namespace, not operational messaging or work tasks.

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

Usage Guidelines4/5

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

Provides explicit usage context: when to call (to create identity), how to authenticate afterward, and how to store the returned secret. Does not explicitly contrast with sibling tools, but the purpose is so distinct that exclusions are not necessary. Mentions alternative auth (agent_key as argument) and equivalent HTTP route.

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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TDQS

A4/5.0

Disambiguation5/5

Every tool targets a clearly distinct mechanism—barriers, budgets, checkpoints, claims, heartbeats, inboxes, leases, work queues, etc. Even closely related pairs like claim/complete, work_done/inbox_ack, and barrier_status/work_status are explicitly differentiated in their descriptions, so an agent can reliably select the right tool.

Naming Consistency4/5

The dominant pattern is object_verb (e.g., checkpoint_get, work_push, seen_add, lease_release), which is consistent and readable. A few single-word verbs (claim, complete, send) and noun-only names (resume_packet, retry_state, whoami) break the pattern, but they are few and still intuitive.

Tool Count2/5

With 33 tools, the surface is well beyond the 25-tool threshold for 'too many' and will feel heavy for agents to explore, even though the tools are organized into subdomains. The scope is broad, but the sheer number makes the server less approachable and increases the chance of misselection.

Completeness5/5

The tool set provides thorough lifecycle coverage across its domains: checkpoints get/put, work queue push/take/done/fail/status, inbox poll/ack/nack/schedule, lease acquire/renew/release, barrier create/signal/status, dedup add/check, watermark get/set, retry state, budget check/record, and idempotency claim/complete. There are no obvious dead ends or missing essential operations.

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