mcpdockery

by Chandrakant1988

Overview Schema Source Related Servers Discussions Admin

pull_image

Pulls a Docker image from a registry without running it. Specify a tag (defaults to alpine) and optional platform for multi-arch images.

Instructions

Pulls a Docker image from a registry (Docker Hub, ECR, GCR, etc.) without running it. Requires prior docker login if the registry needs auth — this tool does not accept credentials.

Defaults to the "alpine" tag (smaller, faster to pull) when no tag is specified. Only pass a different tag (e.g. "latest" or a specific version) if the user explicitly asks for the full/standard image — not every image publishes an "alpine" variant, in which case the pull will fail and you should retry with "latest".

Args: image: repository name, e.g. "nginx" or "myregistry.com:5000/my-app". Can include a tag directly (e.g. "nginx:1.27"), in which case the tag argument is ignored. tag: tag to pull if not already included in image (default "alpine") platform: optional, e.g. "linux/amd64" or "linux/arm64" — force a specific architecture on multi-arch images

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "image": "<image>"
    },
    "name": "pull_image"
  }
}

Input Schema

Name	Required	Default
`tag`	No	alpine
`image`	Yes
`platform`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 7, 2026

TDQS

A4.8/5.0

Behavior4/5

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

With no annotations, the description carries the transparency burden. It clearly discloses authrequirements and the non-credential-accepting behavior, and notes failure with missing alpine variants. It does not explicitly mention that pulling stores the image locally, but the primary side effect is implied well enough.

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 compact and every sentence adds value—no filler, repetition, or irrelevant detail. The structure flows naturally from action to prerequisites to parameter usage.

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?

The tool is simple, and the description covers the essential context: what it does, when authentication is needed, how tags work, and the optional platform parameter. Since an output schema exists, omitting return-value details is acceptable.

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?

Schema coverage is 0%, but the description thoroughly explains all three parameters: image (including embedded tag behavior), tag (default and retry guidance), and platform (optional architecture forcing). It adds substantial meaning beyond the bare schema.

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 clearly states the action ('Pulls a Docker image from a registry') and explicitly distinguishes it from running containers ('without running it'). It is immediately distinguishable from sibling tools like build_image, push_image, and run_container.

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?

The description provides concrete usage guidance: it explains the need for prior docker login when auth is required, states that credentials are not accepted, and gives detailed tag-handling advice including when to use a different tag and when to retry with 'latest'.

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