pictor-mcp

Resize an image

image_resize

Resize images to exact dimensions or by percentage, fit within a box using contain, cover, fill, inside, outside, or pad modes, and optionally change format and filter.

Instructions

Resize by width, height, percentage, or to fit a box. Supports contain, cover, fill, inside, outside and pad fit modes, all resampling filters, and optional format change.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`fit`	No	contain (fit inside, keep ratio), cover (fill and crop), fill (stretch), inside (contain but never enlarge), outside (cover without cropping), pad (contain then pad)	contain
`url`	No	http(s) URL to fetch. Disabled unless PICTOR_ALLOW_NET_FETCH=true.
`path`	No	Path to the image, relative to an allowed input root (or absolute inside one).
`width`	No	Target width in pixels.
`filter`	No	nearest, box, bilinear, hamming, bicubic, lanczos, or auto.
`height`	No	Target height in pixels.
`gravity`	No	Anchor for cover cropping or padding, e.g. center, top, bottom-right.	center
`percent`	No	Scale by this percentage of the original.
`quality`	No	Lossy quality 1-100 (higher is better quality and larger).
`background`	No	RGBA fill used by pad and rotate.
`base64_data`	No	Inline image bytes as base64, optionally a data: URI.
`only_shrink`	No	Never enlarge; leave smaller images untouched.
`output_name`	No	Override the output filename (a safe name is derived if omitted).
`return_image`	No	Embed the resulting image inline so vision-capable clients can see it.
`output_format`	No	Output codec: jpeg, png, webp, avif, tiff, gif, bmp, ico, jpeg2000, qoi, ppm. Defaults to the input format.
`return_base64`	No	Include the base64 payload in the JSON result for clients without file access.
`strip_metadata`	No	Remove EXIF/GPS/ICC metadata. Defaults to the server setting (on).

Output Schema

TableJSON Schema

Name	Required	Description
`ok`	No
`input`	No	Summary of the source image, when one was read.
`notes`	No
`steps`	No
`metrics`	No	Operation-specific measurements (e.g. comparison scores).
`outputs`	No
`operation`	Yes	Tool that produced this result.
`sizeChange`	No
`inlineImageIncluded`	No	True when an image block accompanies this result for vision-capable clients.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Sep 15, 2026

TDQS

B3.3/5.0

Behavior3/5

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

Annotations are entirely absent, so the description carries the full behavioral disclosure burden. It does state supported fit modes, resampling filters, and optional format change, which is meaningful behavioral detail, but it does not disclose side effects, output delivery specifics, network/fetch constraints, or default behavior beyond what appears in the input schema. No contradictions occur.

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 two sentences with no redundancy: it front-loads the core resizing methods, then lists supported modes, filters, and format changes. Every phrase earns its place, and no unnecessary words or examples dilute the meaning.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 17 parameters, a 100% schema-covered input schema, and an output schema, the description does not need to re-explain parameters or return values. However, in a family of 13 sibling tools, it does not add enough disambiguating or decision-level context, and it leaves important usage questions (which input source is required with a network fetch, output naming, whether the result is returned as base64 or filename) unanswered.

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 coverage is 100%, so the baseline is 3 even without extra parameter details in the description. The description adds high-level meaning around resizing by width, height, percentage, or fit box, but it does not enrich individual parameter semantics beyond what the schema already documents.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the action (resize), the resource (image), and the main input modes (width, height, percentage, fit box), plus the supported fit modes and optional format change. It conveys what the tool does and this can help distinguish it from siblings such as image_rotate, but it does not explicitly name or contrast sibling tools, so it is a tier below the strongest examples.

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

Usage Guidelines2/5

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

There is no guidance on when to choose image_resize versus sibling tools like image_thumbnail, image_compress, or image_transform, and no mention of prerequisites, complementary source parameters, or when not to use it. The description simply states the action without helping an agent decide among the many image tools in this family.

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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