MCPFax Agent Continuity

Take work, leased so a dead worker cannot lose it

work_take

Take up to n items, LEASED not deleted — the same lease semantics as lease()/renew()/release(): a holder, a fence token, an expiry. Two workers can never be handed the same item, because one single-threaded Durable Object owns the queue. IF YOUR PROCESS DIES THE LEASE SIMPLY EXPIRES AND THE ITEMS RETURN TO THE QUEUE with attempts incremented; nothing had to stay alive to notice, and that recovery is the point. EACH ITEM CARRIES ITS OWN FENCE, drawn independently on every take: the token you are given for one item tells you nothing about the token another worker was given for another item, and it is not the previous holder's token plus one. The item's ORDER is generation (identical to attempts, the number of times it has been handed out) — that is the number to compare and the number to hand to an external store; the fence is the secret. $0.002 when at least one item is handed to you for the FIRST time; a re-take after your own lease expired is free, exactly like mailbox redelivery. An empty or cancelled queue returns nothing, says so, and costs nothing. Costs $0.002 USDC per call via x402 on Base, and ONLY when at least one item was handed to a worker for the FIRST time (a re-take after a lease expired is free); otherwise the same call returns the full answer and settles nothing. Authenticate with Authorization: Bearer , or pass agent_key as an argument if your host cannot set headers. Equivalent HTTP route: POST /v1/work/take.

Input Schema

TableJSON Schema

Name	Required	Description
`n`	No	How many items to take. 1..25. Default 1. Example: '5'.
`holder`	No	Who is taking — an instance id you choose, exactly as with lease(). Default 'worker'. Example: 'worker-3'.
`queue_id`	Yes	The queue to take from. Alias: job_id — a job and its work queue are the same thing. Example: 'permit-batch-2026-08'.
`agent_key`	No	Your agent_secret, if your MCP host cannot set the Authorization header. Prefer the header.
`lease_seconds`	No	How long you hold them before they return to the queue. Default 300, min 5, max 86400. Example: '300'.

TDQS

A4.2/5.0

Behavior5/5

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

The description covers critical behaviors beyond the annotations: leases expire and items return, fence tokens are independent, generation equals attempts, empty queues return nothing, and pricing only applies on first-time handouts. It also details authentication methods and the equivalent HTTP route — all valuable context that annotations (all false) do not provide.

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

Conciseness2/5

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

The description is a single, extremely long paragraph with repeated pricing information and all-caps emphasis. It lacks bullet points or structured sections, making it harder to parse quickly. Several sentences could be merged or removed without losing value, so it fails the 'every sentence earns its place' test.

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?

With no output schema, the description thoroughly explains what happens on success, on empty/cancelled queues, and on re-takes after lease expiry. It also covers pricing, authentication, and the HTTP route, making the tool fully self-contained for an agent to invoke correctly.

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

Parameters3/5

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

Schema description coverage is 100%, so the baseline is 3. The description adds background on lease semantics and examples (e.g., n up to 25, lease_seconds defaults), but it does not go beyond the parameter-level details already present in the schema. It therefore meets the baseline without meaningful enrichment.

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 'Take up to n items, LEASED not deleted' — a specific verb, resource, and lease semantics that clearly distinguish it from sibling lease management tools. It also explicitly contrasts with lease()/renew()/release() and mentions the same behavior, leaving no ambiguity about what work_take does.

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?

The description explains when items return to the queue (lease expiry) and what happens on empty/cancelled queues, giving clear operational context. However, it does not explicitly name alternative tools like work_done or work_fail for when NOT to use this tool, so the guidance stays implied rather than explicitly exclusions.

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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