typesafe-mcp
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@typesafe-mcpClassify this support ticket as billing, bug, or feature request."
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
typesafe-mcp
A standard Model Context Protocol (MCP)
server that exposes TypeSafe AI's Jev decision model as typed tools —
publishable to npm and runnable anywhere with npx or bunx.
npx -y @devbux/typesafe-mcpWhat is Jev?
Jev is TypeSafe AI's System One decision model. It never generates prose. Instead, you give it:
a
state— a situation described as text or structured JSON, anda set of typed questions about that state,
and Jev returns typed answers with calibrated probabilities:
Question type | You define | Jev returns |
| 2–255 labelled options (each with an optional description) | the chosen option, a confidence value, and a probability for every option |
| an ordered scale of level descriptions (at least 2) | a numeric score on your scale, confidence, and per-level probabilities |
| a proposition (optionally with true/false descriptions) | a calibrated probability (0..1) that the proposition is true |
| what to find, and in which image | the target's bounding-box edges ( |
Questions can also read images: pass pictures in an assets map and
reference them from the state, instructions, or criteria — see
Images. instructions and criteria accept structured JSON
(objects/arrays), not just strings.
Because the output is structured and calibrated rather than free text, Jev is well suited to routing, triage, moderation, risk scoring, prioritisation, and any other "decide, don't chat" step inside an agent workflow.
Related MCP server: jev-mcp
Requirements
Node.js >= 18 (or Bun) to run the server.
A TypeSafe AI API key (see Getting an API key).
Install & run
The server speaks MCP over stdio, so you normally don't run it by hand — your MCP client launches it. The commands below are how clients (or you, for a quick smoke test) start it.
npx (Node)
TYPESAFE_API_KEY=your-key npx -y @devbux/typesafe-mcpbunx (Bun)
TYPESAFE_API_KEY=your-key bunx @devbux/typesafe-mcpGlobal install (npm)
npm install -g @devbux/typesafe-mcp
TYPESAFE_API_KEY=your-key typesafe-mcpGlobal install (Bun)
bun add -g @devbux/typesafe-mcp
TYPESAFE_API_KEY=your-key typesafe-mcpThe server starts even when
TYPESAFE_API_KEYis not set, so clients can still list its tools; each tool call then returns a clear error naming the missing variable instead of crashing.
Getting an API key
Create an API key in the TypeSafe console at
typesafe.ai, then expose it to the server as the
TYPESAFE_API_KEY environment variable. Never commit your key to source
control.
MCP client configuration
Generic (mcpServers JSON)
Most MCP clients (Claude Desktop, and many others) accept a configuration
like this — see also examples/mcp-config.json:
{
"mcpServers": {
"typesafe": {
"command": "npx",
"args": ["-y", "@devbux/typesafe-mcp"],
"env": {
"TYPESAFE_API_KEY": "YOUR_TYPESAFE_API_KEY"
}
}
}
}Using Bun instead:
{
"mcpServers": {
"typesafe": {
"command": "bunx",
"args": ["@devbux/typesafe-mcp"],
"env": {
"TYPESAFE_API_KEY": "YOUR_TYPESAFE_API_KEY"
}
}
}
}Claude Code
claude mcp add typesafe \
-e TYPESAFE_API_KEY=YOUR_TYPESAFE_API_KEY \
-- npx -y @devbux/typesafe-mcpCursor / VS Code
Cursor and VS Code use the same mcpServers JSON shape above (Cursor:
.cursor/mcp.json or Settings → MCP; VS Code: .vscode/mcp.json uses a
top-level "servers" key with the same per-server fields). Paste the generic
config and replace the placeholder key.
Configuration
Environment variable | Default | Description |
| (unset) | Bearer API key for the TypeSafe AI API. Required for tool calls; the server still starts without it. |
|
| Base URL of the TypeSafe AI API. |
|
| Jev model id to request. Can be overridden per call with the tools' optional |
Tools
All tools return the Jev API response as JSON text content. Errors (missing
API key, HTTP 401/403/429/5xx, network failures, timeouts) are returned as MCP
tool errors (isError) with a clear message that includes the HTTP status —
never your API key.
Tool | Inputs | Output |
|
| All answers in one call: |
|
| One Choice answer under the name |
|
| One Score answer under the name |
|
| One Noul answer (probability 0..1) under the name |
|
| One Box answer ( |
| (none) |
|
assets and long_context are described under Images and
Long context.
Question shapes for jev_decide
{
"type": "choice",
"instructions": "Which department should handle this?",
"criteria": { "billing": "Payments and invoices", "technical": null }
}{
"type": "score",
"instructions": "How urgent is this?",
"criteria": ["not urgent", "low", "medium", "high", "critical"]
}{
"type": "noul",
"instructions": "Is a refund likely to be requested?"
// "criteria" is optional for noul and omitted when not provided
}{
"type": "box",
"instructions": "the coffee mug in `kitchen_photo`"
// box takes no criteria; it needs an image in the request and Jev 1.14
}Images
An image can go anywhere text can go in a request: in the state, in a
question's instructions, and in its criteria. Every decision tool accepts
an optional assets argument — a map from a reference string to an
image, base64-encoded:
{
"state": "Doorbell camera frame: doorbell_img",
"questions": {
"person_at_door": {
"type": "noul",
"instructions": "Is a person visible in doorbell_img?"
},
"person_where": {
"type": "box",
"instructions": "the person in `doorbell_img`"
}
},
"assets": {
"doorbell_img": { "data_base64": "<base64, no data: prefix>", "format": "jpg" }
},
"model": "jev-1.14.0"
}Rules from the TypeSafe docs:
Write each asset's reference wherever the image belongs (whole value or inside a longer string). Every asset must be referenced at least once, or the API returns
400— this server checks that before sending. Use distinctive references (a UUID is safest): references match as plain text, so a short one likecatcould also match insidecategory.Formats: PNG or JPEG only, still images. Each image: at most 16 MiB, each side 280–1568 px; the request body and all images together are capped at 32 MiB. Images are never resized by the API — prepare them (upright, within the limits) before sending.
Images are an opt-in "danger zone" feature: the server automatically sends the
TypeSafe-Danger-Zone-Images: trueheader whenever a request has assets or a Box question. TypeSafe marks these features experimental — formats and limits may change between releases.Jev 1.13 and 1.14 both accept images. Box questions need Jev 1.14: send
jev-1.14.0orjev-previewas the model (jev_boxdefaults tojev-1.14.0). A Box answer is always a box, even when the target is absent — pair it with anoulpresence check when that matters.The API also accepts multipart uploads; MCP tool calls carry JSON, so this server always uses the base64 form.
Long context
Jev's default context limits are 64k tokens per request and 32k per
question. Any decision tool accepts long_context: true, which sends the
TypeSafe-Danger-Zone-Long-Context: true header and raises both limits to
262k tokens. TypeSafe marks this experimental too: it is slower and less
accurate, so use it only when a request does not fit the default limits.
Worked example
A support ticket comes in. In one jev_decide call you can route it,
rate its urgency, and estimate refund risk:
Request (tool jev_decide):
{
"state": "Customer writes: 'I was charged twice for my subscription this month and I want my money back today. This is the second billing problem in three months.'",
"questions": {
"department": {
"type": "choice",
"instructions": "Which department should handle this ticket?",
"criteria": {
"billing": "Charges, invoices, payments and refunds",
"technical": "Product bugs and technical problems",
"sales": "Pricing, plans and new purchases"
}
},
"urgency": {
"type": "score",
"instructions": "How urgent is this ticket?",
"criteria": ["not urgent", "low", "medium", "high", "critical"]
},
"refund_likely": {
"type": "noul",
"instructions": "Is this customer likely to request a refund?"
}
}
}Response (shape; exact values come from the live model):
{
"answers": {
"department": {
"type": "choice",
"choice": "billing",
"confidence": 0.91,
"probabilities": { "billing": 0.91, "technical": 0.06, "sales": 0.03 }
},
"urgency": {
"type": "score",
"score": 4,
"confidence": 0.8,
"probabilities": { "1": 0.02, "2": 0.05, "3": 0.13, "4": 0.55, "5": 0.25 }
},
"refund_likely": {
"type": "noul",
"noul": 0.72
}
},
"model": "jev-1.13.0",
"usage": { "input_tokens": 120, "output_tokens": 45 }
}Development
git clone https://github.com/devbux/typesafe-mcp.git
cd typesafe-mcp
npm install
npm run dev # run the server from source with tsx (stdio)
npm run typecheck # tsc --noEmit
npm test # vitest (fake fetch — no live network calls)
npm run build # bundle to dist/index.js with tsup
npm start # run the built serverProject layout:
src/
index.ts stdio bootstrap
server.ts MCP server + the six jev_* tools (zod-validated)
config.ts environment parsing (TYPESAFE_*)
jev/
client.ts typed JevClient for POST /v1/systemone and GET /v1/models
types.ts request/response types for the Jev API
test/
client.test.ts JevClient + config unit testsPublishing
Releases are published to npm by the Publish to npm GitHub Action
(.github/workflows/publish.yml):
Bump the version in
package.json, updateCHANGELOG.md, and push.Create a GitHub Release for the new version tag (or run the workflow manually with
workflow_dispatch).The workflow runs typecheck, tests, and build, then publishes with
npm publish --provenance --access public.
Notes:
The workflow expects an
NPM_TOKENrepository secret (an npm automation token for an account/organisation that owns the@devbuxscope).Provenance is enabled (
id-token: writepermission +--provenance), so each published version is linked to its GitHub Actions build.This is a scoped package (
@devbux/typesafe-mcp);publishConfig.accessis set topublicinpackage.jsonso releases are publicly installable.prepublishOnlyalso runs typecheck, tests, and build for manual publishes.
License
MIT © 2026 devbux
Available Tools
6 toolsjev_boxJev: box question (find where something is in an image)A
Ask Jev a single Box question: locate one target in an image. Returns the box edges as fractions of the image size (top, bottom, left, right, each 0..1) plus a confidence value, under the question name "answer". The image must be in the request: reference it from the state or the instructions and pass it in assets. Box needs Jev 1.14, so this tool sends jev-1.14.0 unless you pass another model (jev-preview also works). A Box answer is always a box, even when the target is absent; pair it with jev_noul when you need a presence check.
| Name | Required | Description | Default |
|---|---|---|---|
| model | No | Optional Jev model id override (default: jev-1.14.0, because Box requires Jev 1.14). | |
| state | Yes | The situation: text, a JSON object, or a JSON array. Reference the image here (or in the instructions) where it belongs. | |
| assets | No | Images keyed by reference string. Write each reference in the state, instructions, or criteria where the image belongs. PNG or JPEG only, base64-encoded with no data: prefix. API limits: 16 MiB per image, 280-1568 px per side. | |
| instructions | Yes | What to find, and in which image: e.g. "the coffee mug in `photo`". | |
| long_context | No | Opt into Jev's 262k long-context limits (an experimental danger-zone feature: slower and less accurate). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden and does well: it discloses the always-returns-a-box behavior, the required model version and default override, the image-in-request requirement, and the answer key/return shape. It omits any mention of permissions, latency, or failure modes when the image is missing.
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?
The core capability and return format are front-loaded in the first two sentences, with the model-default caveat and the jev_noul pairing placed after. It is a touch dense with parentheticals but every sentence carries actionable information.
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 5-param, nested-object tool with no output schema, the description supplies the missing return-value detail (top/bottom/left/right as 0..1 fractions, confidence, under "answer"), the image-in-request requirement, and the model-version constraint. Nothing an agent needs to call it correctly is absent.
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%, so the baseline is 3, but the description adds value beyond the schema by explaining *why* model defaults to jev-1.14.0 ("Box needs Jev 1.14") and by clarifying that the image is referenced from state/instructions and passed via assets. That reasoning is not derivable from the schema alone.
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?
The description states a specific verb and resource — "locate one target in an image" and return box edges — and distinguishes the tool from the sibling `jev_noul` by framing Box as a localization tool versus a presence check. An agent can tell it apart from `jev_decide`/`jev_score`/`jev_noul` without opening any schema.
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?
It gives an explicit selection rule: "pair it with jev_noul when you need a presence check," plus the caveat that a Box answer is always a box even when the target is absent. It doesn't explicitly contrast with jev_decide/jev_choice/jev_score, so the routing across the full sibling set is incomplete.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
jev_choiceJev: choice questionA
Ask Jev a single Choice question: pick exactly one option from a labelled set. Returns the chosen option, a confidence value, and calibrated probabilities for every option. The answer is returned under the question name "answer".
| Name | Required | Description | Default |
|---|---|---|---|
| model | No | Optional Jev model id override (default: jev-latest). | |
| state | Yes | The situation to decide about: text, a JSON object, or a JSON array. | |
| assets | No | Images keyed by reference string. Write each reference in the state, instructions, or criteria where the image belongs. PNG or JPEG only, base64-encoded with no data: prefix. API limits: 16 MiB per image, 280-1568 px per side. | |
| options | Yes | Object mapping each option label to a description (string, structured object/array, or null; 2-255 options). An option can be defined by example pictures: put image references in its description. | |
| instructions | Yes | What Jev should decide: plain-language text, or structured JSON. | |
| long_context | No | Opt into Jev's 262k long-context limits (an experimental danger-zone feature: slower and less accurate). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral-disclosure burden. It usefully states the return shape (chosen option, confidence, calibrated probabilities, and answer under the key "answer"), but does not discuss side effects, permissions, latency, cost, or failure behavior.
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?
The description is three tight sentences with no wasted language. Purpose is front-loaded, followed by return behavior and a key output detail.
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?
The description covers the core purpose and return shape, and the schema fully documents all six parameters. Given the absence of annotations and output schema, it is substantially complete, though it could say more about operational constraints or alternatives.
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%, so parameter meaning is already well documented in the schema. The description reinforces that options come from a labelled set and that the answer is keyed as "answer", but adds little else beyond the structured parameter descriptions.
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?
The description states a specific operation: asking Jev a single-choice question and picking exactly one option from a labelled set. It clearly defines the resource and constraint, but does not explicitly contrast this with sibling tools such as jev_decide or jev_score.
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 single-choice selection from labelled options, which gives some usage context. However, it does not say when to use this instead of jev_decide or jev_score, nor does it state exclusions or alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
jev_decideJev: decide (multiple typed questions)A
Ask TypeSafe AI's Jev decision model one or more typed questions (choice, score, noul and/or box) about a state in a single call. Returns typed answers with calibrated probabilities. The state may be text or structured JSON. Images: pass them in assets and write each image's reference in the state, instructions, or criteria where it belongs.
| Name | Required | Description | Default |
|---|---|---|---|
| model | No | Optional Jev model id override (default: jev-latest). | |
| state | Yes | The situation to decide about: text, a JSON object, or a JSON array. | |
| assets | No | Images keyed by reference string. Write each reference in the state, instructions, or criteria where the image belongs. PNG or JPEG only, base64-encoded with no data: prefix. API limits: 16 MiB per image, 280-1568 px per side. | |
| questions | Yes | Map of question name to typed question. Each question has a type (choice | score | noul | box), instructions, and criteria: choice = object of option label -> description (string, structured object/array, or null; 2-255 options); score = array of at least 2 ordered level descriptions (strings or structured entries); noul = optional object of true/false descriptions; box = instructions only, no criteria (finds where something is in an image). Instructions may be text or structured JSON. | |
| long_context | No | Opt into Jev's 262k long-context limits (an experimental danger-zone feature: slower and less accurate). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry behavioral disclosure; it does say the call returns typed answers with calibrated probabilities and accepts text or structured state, which is more than nothing. It says nothing about latency/cost, batching limits, determinism, or failure modes, and leaves long-context behavior to the schema.
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?
Three compact sentences, front-loaded with what the tool does and what it returns, then the image caveat. No filler, though the image sentence is somewhat dense and could be trimmed since the schema repeats it.
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 5-param nested tool with no output schema, the description covers purpose, accepted state formats, the four question types, and the general return shape (typed answers with calibrated probabilities). Missing detail on the answer payload structure and multi-question semantics is partly mitigated by the exhaustive schema text.
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%, so the schema already documents all five parameters. The description's image note (pass in `assets` and reference each image in state/instructions/criteria) largely restates what the `assets` schema description says, adding little beyond the structured field. Baseline 3 applies.
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 (ask the Jev decision model typed questions) and enumerates the question types (choice, score, noul, box), which implicitly maps to the sibling tools. It signals batching ('one or more ... in a single call') without naming jev_choice/jev_score/etc. as alternatives, so differentiation is present but inferential.
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 phrase 'one or more typed questions ... in a single call' hints that this is the multi-question entry point, and the image guidance covers one specific case. But there is no explicit 'use this instead of jev_choice when...' routing or statement of when a single-type sibling is preferable.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
jev_list_modelsJev: list modelsA
List the TypeSafe AI models available to the configured API key (name, description, release date).
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the burden. It correctly signals a read-only enumeration scoped to the API key and discloses the returned fields, but says nothing about failure modes (invalid/missing key), result counts, pagination, or ordering.
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 sentence with the operation and scope front-loaded and the return fields trailing as a parenthetical. Nothing is padded or repeated.
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?
The tool is simple, parameterless, and has no output schema, so the description covering the resource, the key scoping, and the fields returned is close to sufficient. Only the absence of any error/empty-result behavior keeps it from being fully complete.
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?
The tool takes zero parameters, so there is nothing to disambiguate and the baseline of 4 applies. The parenthetical list of returned fields is a small bonus but is return-value information rather than parameter semantics.
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 (List) and resource (TypeSafe AI models) plus the scoping condition (available to the configured API key) and enumerates the returned fields. The sibling names (jev_decide, jev_choice, jev_score, jev_noul, jev_box) are opaque and share no resource domain, so no sibling differentiation is possible or needed here.
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?
Usage is implied by 'available to the configured API key' — an agent can infer this is a discovery/introspection call — but the description never states when to call it (e.g. before invoking a model) or names any alternative. No exclusions or prerequisites are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
jev_noulJev: noul questionA
Ask Jev a single Noul question: estimate the probability (0..1) that a proposition about the state is true. Returns the calibrated probability under the question name "answer".
| Name | Required | Description | Default |
|---|---|---|---|
| model | No | Optional Jev model id override (default: jev-latest). | |
| state | Yes | The situation to decide about: text, a JSON object, or a JSON array. | |
| assets | No | Images keyed by reference string. Write each reference in the state, instructions, or criteria where the image belongs. PNG or JPEG only, base64-encoded with no data: prefix. API limits: 16 MiB per image, 280-1568 px per side. | |
| criteria | No | Optional descriptions keyed by "true" / "false" explaining what each outcome means. Values may be strings, structured objects/arrays, or null, and may hold image references. | |
| instructions | Yes | The proposition Jev should assess: plain-language text, or structured JSON. | |
| long_context | No | Opt into Jev's 262k long-context limits (an experimental danger-zone feature: slower and less accurate). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the burden alone. It usefully discloses the return shape (a single calibrated probability under the key 'answer'), which is real behavioral value. However it says nothing about cost, latency, failure modes, or how the optional criteria/assets/long_context alter the estimate — notable gaps for an un-annotated inference call.
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, front-loaded with the verb and resource, then the return contract. Nothing wraps around or repeats the name; every clause earns its place.
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?
It covers the core call and its return value adequately for a tool with no output schema, but with six parameters including nested objects (assets, criteria) and no annotations at all, the description leaves the optional parameters' effect on the estimate unexplained and gives no guidance on choosing among the several jev_* siblings.
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%, so baseline would be 3, and the description genuinely adds semantics by linking the two required parameters: the proposition in 'instructions' is evaluated against 'state'. That relational meaning is not spelled out in the schema descriptions, which treat each parameter separately.
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 — 'ask Jev a single Noul question' — and pins down the operation as estimating a probability in [0,1] that a proposition about the state is true. It also names the return key, so the agent knows exactly what comes back. It stops short of naming how it differs from siblings like jev_decide or jev_score, which is why it isn't a 5.
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?
Usage is only implied: the binary true/false probability framing suggests when this fits, but there is no explicit 'use this instead of jev_choice/jev_score when...' statement and no prerequisites or exclusion cases. An agent must infer the boundary from the sibling names alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
jev_scoreJev: score questionA
Ask Jev a single Score question: rate the state on an ordered scale you define. Returns a numeric score, a confidence value, and probabilities per level. The answer is returned under the question name "answer".
| Name | Required | Description | Default |
|---|---|---|---|
| model | No | Optional Jev model id override (default: jev-latest). | |
| state | Yes | The situation to decide about: text, a JSON object, or a JSON array. | |
| assets | No | Images keyed by reference string. Write each reference in the state, instructions, or criteria where the image belongs. PNG or JPEG only, base64-encoded with no data: prefix. API limits: 16 MiB per image, 280-1568 px per side. | |
| levels | Yes | Ordered level descriptions, lowest to highest (at least 2). Each level may be a string or a structured entry, and may hold image references as examples. | |
| instructions | Yes | What Jev should rate: plain-language text, or structured JSON. | |
| long_context | No | Opt into Jev's 262k long-context limits (an experimental danger-zone feature: slower and less accurate). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations and no output schema, the description carries the burden well by disclosing the return payload (numeric score, confidence, per-level probabilities) and the key under which the answer is nested ('answer'). It omits cost/latency/limits behavior and doesn't state that only one question per call is processed beyond the word 'single'.
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?
Three tight sentences, front-loaded with the action and rating semantics, then the return shape. Every sentence carries information an agent needs; nothing is padding.
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 6-parameter tool with nested objects and no output schema, the description covers what the tool does and what comes back, which is the main gap the schema leaves. It could say more about the levels ordering constraint interacting with outputs, but nothing essential for correct invocation is missing.
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%, so model, assets, levels, instructions, and long_context are already documented in the schema. The description only restates that the scale is ordered and defined by the caller, adding little beyond the parameter documentation — the baseline 3.
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: ask a Jev Score question that rates a state on an ordered scale the caller defines, and it names the shape of the result. This is clearly distinct from the jev_decide/jev_choice siblings by virtue of the ordered-scale semantics, though no sibling is named 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?
The phrase 'a single Score question' plus 'ordered scale you define' implies when this tool fits (grading/rubric-style evaluation), but the description never says when to prefer jev_decide or jev_choice instead, nor any prerequisites. Usage is inferable rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
5 tool updates
v0.2.3- Changed
jev_box4 fields changed- removed
Input schema / additionalPropertiesRemoved value: -false - removed
Input schema / properties / assets / additionalProperties / additionalPropertiesRemoved value: -false - added
Input schema / properties / assets / propertyNamesAdded value: +{ + "type": "string" +} - changed
Input schema / properties / state / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + } +]
- Changed
jev_choice7 fields changed- removed
Input schema / additionalPropertiesRemoved value: -false - removed
Input schema / properties / assets / additionalProperties / additionalPropertiesRemoved value: -false - added
Input schema / properties / assets / propertyNamesAdded value: +{ + "type": "string" +} - changed
Input schema / properties / instructions / anyOfPrevious value: -[ - { - "minLength": 1, - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - }, - { - "type": "null" - } -]New value: +[ + { + "minLength": 1, + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + }, + { + "type": "null" + } +] - changed
Input schema / properties / options / additionalProperties / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - }, - { - "type": "null" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + }, + { + "type": "null" + } +] - added
Input schema / properties / options / propertyNamesAdded value: +{ + "type": "string" +} - changed
Input schema / properties / state / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + } +]
- Changed
jev_decide7 fields changed- removed
Input schema / additionalPropertiesRemoved value: -false - removed
Input schema / properties / assets / additionalProperties / additionalPropertiesRemoved value: -false - added
Input schema / properties / assets / propertyNamesAdded value: +{ + "type": "string" +} - removed
Input schema / properties / questions / additionalProperties / additionalPropertiesRemoved value: -false - changed
Input schema / properties / questions / additionalProperties / requiredPrevious value: -[ - "type" -]New value: +[ + "type", + "instructions" +] - added
Input schema / properties / questions / propertyNamesAdded value: +{ + "type": "string" +} - changed
Input schema / properties / state / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + } +]
- Changed
jev_noul7 fields changed- removed
Input schema / additionalPropertiesRemoved value: -false - removed
Input schema / properties / assets / additionalProperties / additionalPropertiesRemoved value: -false - added
Input schema / properties / assets / propertyNamesAdded value: +{ + "type": "string" +} - changed
Input schema / properties / criteria / additionalProperties / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - }, - { - "type": "null" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + }, + { + "type": "null" + } +] - added
Input schema / properties / criteria / propertyNamesAdded value: +{ + "type": "string" +} - changed
Input schema / properties / instructions / anyOfPrevious value: -[ - { - "minLength": 1, - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - }, - { - "type": "null" - } -]New value: +[ + { + "minLength": 1, + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + }, + { + "type": "null" + } +] - changed
Input schema / properties / state / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + } +]
- Changed
jev_score6 fields changed- removed
Input schema / additionalPropertiesRemoved value: -false - removed
Input schema / properties / assets / additionalProperties / additionalPropertiesRemoved value: -false - added
Input schema / properties / assets / propertyNamesAdded value: +{ + "type": "string" +} - changed
Input schema / properties / instructions / anyOfPrevious value: -[ - { - "minLength": 1, - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - }, - { - "type": "null" - } -]New value: +[ + { + "minLength": 1, + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + }, + { + "type": "null" + } +] - changed
Input schema / properties / levels / items / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - }, - { - "type": "null" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + }, + { + "type": "null" + } +] - changed
Input schema / properties / state / anyOfPrevious value: -[ - { - "type": "string" - }, - { - "additionalProperties": {}, - "type": "object" - }, - { - "items": {}, - "type": "array" - } -]New value: +[ + { + "type": "string" + }, + { + "additionalProperties": {}, + "propertyNames": { + "type": "string" + }, + "type": "object" + }, + { + "items": {}, + "type": "array" + } +]
6 tool updates
v0.2.2- First observed
jev_box - First observed
jev_choice - First observed
jev_decide - First observed
jev_list_models - First observed
jev_noul - First observed
jev_score
TDQS
Scored across 6 tools
The four question-type tools (choice, score, noul, box) each map to a distinct answer type, and the box description explicitly directs users to pair it with noul for presence checks. The only overlap is jev_decide, which bundles the same question types in a batch call; the descriptions clarify this, but an agent could still reasonably default to jev_decide for everything, blurring the boundary.
All tools share a consistent 'jev_' prefix and snake_case, so the set reads predictably. Minor deviation: jev_list_models is verb_noun while jev_choice/score/noul/box are bare nouns naming question types, with jev_decide as a verb — mostly cosmetic.
Six tools is well-scoped for a decision-model API: one per question type, a batch aggregator, and a model lister. No tool feels redundant or missing at this size.
The surface covers all four documented answer types plus batching and model discovery, which is the core of the domain. Minor gaps remain — no per-model capability introspection, usage/credit reporting, or error/diagnostic helper — but core workflows are covered.
Maintenance
Related MCP Connectors
Grade essays, check resumes, and ask typed yes/no, choice and rubric questions, powered by Jev.
Typed-question decisions from Jev: classify, moderate, route models and guard tool calls.
Calibrated judgments for text: yes/no probabilities, picks from your options, or scores.
Jev-powered decisions, web search, PDF/web to Markdown, summarize. From $0.001, no API key.
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