jam-annotate

jam-annotate

The deliverable is a screenshot Jam a reviewer reads in five seconds: a box on the broken thing, a number that matches a line in the description, secrets redacted. jam create jam draws the marks into the image before upload; jam agent-context prints the full payload schema.

A request to create or share a Jam authorizes the upload. For local-only annotation or redaction, use the available image tools and return a local file. Do not upload it or sign in to Jam.

Set up the CLI

command -v jam >/dev/null || echo "jam is not installed"
export PATH="$HOME/.local/bin:$PATH"
jam auth status --json || jam auth login

If jam is not on PATH, stop and ask the user to install it from https://jam.dev/docs/cli, then continue. Do not install it yourself.

Exit code 3 means not signed in. With no browser (CI, a cloud agent), ask the user to set JAM_TOKEN to a personal access token from https://jam.dev/s/settings/mcp as a secret. Never write a token to a file.

Pick the mark

Five kinds. Pick by what the mark says:

Kind	Says	Numbered
box	this element is the subject	yes
arrow	from here, look there (direction)	yes
text	a fact with no element to point at	no
redact	this region must not leave the screen	no
blur	this region is not the point	no

Get coordinates right

Coordinates are pixels of the image file, origin top-left. They are not CSS pixels. A retina capture is 2x, so a button at CSS (120, 340) sits at image (240, 680).

1. Capture the viewport, not the full page, so element bounds and the image share an origin.
2. Read the image size (the PNG header, or your driver's screenshot metadata) and divide by the viewport width. That ratio is the scale.
3. Take element bounds from the driver (Playwright locator.boundingBox(), CDP DOM.getBoxModel) and multiply every number by the scale.
4. Pad a box 6 to 10 CSS pixels beyond the element so the outline does not sit on the element's own border.

With only an image file and no driver, read its pixel size, place the marks by eye in image pixels with generous boxes, and say in the reply that the positions are estimates.

The CLI refuses a mark that falls outside the image and names the index. A refusal almost always means the scale was skipped.

Know what a mark covers

A box or arrow draws more than its outline. Below, u is the image width divided by 1440, at least 1, and every size is image pixels.

• Badge: a circle of radius 14u centered on the box's top-left corner, or on the arrow's from. Its inner quarter sits on whatever is in that corner: an icon, an avatar, the first letter.
• Box label: a chip 29u tall whose bottom edge is 7u above the box, starting 21u right of the box's left edge. When the box is less than 36u from the top of the image, the chip goes inside the box's top edge and covers its content.
• Arrow label: a chip 29u tall, centered vertically on from, starting 21u to its right.
• A chip is about 8.4u wide per character, plus 14u.
• At an image edge, the CLI moves badges and chips inward so they stay in the image. There they cover more of the box than the numbers above say.

So a labelled box needs 36u of empty space above it. Rows in a list, table or activity feed are closer than that: a label on one row covers the row above it, and a label on the next row covers the first row's text.

Compose

• One mark per fact you will write. Three to five marks. More is a video.
• Nothing a mark draws may cover text the reader needs, including another mark's subject. Before you add a label, check its chip and badge against the section above.
• For neighbors (stacked rows, adjacent buttons), box each one without a label and put the words in the numbered description. When the labels must be on the image, use arrows whose tails sit in an empty margin with room for the chip to their right.
• Pad a box at least 14u on the left when an icon or avatar starts the element, so the badge does not hide it.
• Box the element that is wrong. Arrow only when direction is the point: where a click should have led, which control changed which value. Put the tail in empty space and the head on the edge of the target, not its center.
• Text is for a fact with no element: "nothing happened after click". Place it in empty space near the area it describes.
• Redact first, generously: emails, names, avatars, tokens, internal URLs, customer identifiers. Redact the whole row, not the word.
• Blur is for clutter, not secrets: a sidebar, a list of unrelated rows, a face in a demo. It softens the region so the eye skips it. Large text stays legible through a blur, so anything that must not leave the screen is a redact.
• Order is the story. Numbers follow payload order, so list the marks in the order the description tells them.
• Labels are five words or fewer, Latin text, no trailing period. The sentence goes in the description.
• Color carries meaning, one color per meaning. Default lime is "look here". Use strawberry for the broken thing when there is more than one mark. Other swatches: grape, blueberry, mint, lemon, black.
• Marks are drawn on the primary screenshot only. A secondaryScreenshotPath uploads as-is, so a redaction on the primary does not cover it. Attach a secondary only when it shows none of what you redacted; otherwise redact it with an image tool first, or leave it out.

Payload

The capture below is 2x, so a 1440×900 viewport is a 2880×1800 image and every coordinate is doubled.

Write the payload to a file with your file-writing tool (for example payload.json), then run jam create jam @payload.json. The URL, title and description come from the user or the page, so they never go into a shell argument.

{
  "url": "https://app.example.com/checkout",
  "title": "Pay button does nothing on retry",
  "description": "1. The Pay button, clicked twice.\n2. Where the confirmation should have appeared.\nCard number redacted.",
  "screenshotPath": "./checkout.png",
  "screenDimensions": { "width": 1440, "height": 900 },
  "annotations": [
    { "type": "redact", "x": 1200, "y": 640, "width": 560, "height": 48 },
    { "type": "blur", "x": 0, "y": 0, "width": 480, "height": 1800 },
    { "type": "box", "x": 1180, "y": 1120, "width": 320, "height": 88, "label": "Pay, clicked twice", "color": "strawberry" },
    { "type": "arrow", "from": { "x": 600, "y": 1400 }, "to": { "x": 1440, "y": 980 }, "label": "no confirmation here" }
  ]
}

Write the description so its numbers are the badge numbers: "1." is the first box or arrow in the payload, "2." the second. Redactions, blurs and text notes never take a number.

After

1. Read the receipt: id, url, kind. If the command failed, say so and fix the payload. Never hand over a link you did not get.
2. Look at what was drawn: jam get screenshots <id> --out <dir>, then open the PNG. If a chip or badge covers text the claim depends on, fix the payload, create the Jam again, and share only the new link. Ask the human before you delete the first Jam, because a deleted Jam cannot come back.
3. Link it when there is something to link. With a pull request or ticket the screenshot belongs to: jam update jam <id> --resource <url>. For one Jam per UI state, join them with jam update jam <id> --mark-related <other jam> --type relates_to. Never attach a URL that carries a token: the share page can be public.
4. Return the link with the claim it supports. Post it on a PR or ticket only when the user requested that destination.

Send feedback to Jam

When this skill, a Jam MCP tool, a jam command or a Jam doc was wrong, stale or confusing, or worked unusually well, tell Jam. Send it yourself: Jam's agents read it, so it needs no approval.

Call the submitFeedback MCP tool with body, category and subject.

When MCP is unavailable, use the CLI:

jam feedback "<what you were doing, what you expected, what happened, the mistake>" --category <skills|mcp|cli|docs> --subject <skill name, tool name or command>

• Jam surfaces only, not the user's code or other tools.
• At most once per session, and never for a slip you corrected yourself.
• No secrets, customer data, source code, stack traces or recording content.