pictor-mcp

Create a thumbnail

image_thumbnail

Produce exact-size thumbnails by automatically cropping to the visually salient region using attention or entropy, avoiding blind center crops.

Instructions

Produce a thumbnail of an exact size, choosing the crop by saliency (attention or entropy) instead of blindly taking the centre.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`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).
`size`	No	Exact (width, height) of the thumbnail.
`method`	No	attention (edge energy), entropy (local detail) or center.	attention
`quality`	No	Lossy quality 1-100 (higher is better quality and larger).
`sharpen`	No	Unsharp-mask amount applied after resizing; 0 disables.
`base64_data`	No	Inline image bytes as base64, optionally a data: URI.
`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.
`max_dimension`	No	Shorter alternative: fit within a square of this size, keeping ratio.
`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

B3.1/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only says 'Produce a thumbnail' without mentioning side effects, permissions, whether the original is modified, or if output is returned as a file vs inline. The output schema documents return values but not behavior like overwriting or network access.

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 a single sentence of about 20 words, front-loading the core function and its unique feature. Every word contributes; there is no filler or repetition of schema details.

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?

For a tool with 13 parameters, the description is minimal, but the schema fully documents each parameter and there is an output schema covering return values. The high-level purpose is clear, yet the description lacks usage context (e.g., when to use saliency vs center) and doesn't mention that all parameters are optional. It's adequate but not comprehensive.

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 all 13 parameters are documented. The description adds minimal context: it references 'exact size' and 'saliency (attention or entropy)' which align with the size and method parameters but don't go beyond the schema. This meets the baseline for high coverage.

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 states a clear verb ('Produce') and resource ('thumbnail'), and specifies the key differentiator: saliency-based cropping 'instead of blindly taking the centre.' This distinguishes it from a simple center-crop tool, though it doesn't name sibling tools explicitly. The purpose is unambiguous and specific.

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?

No guidance is provided on when to use this tool versus alternatives like image_resize or image_crop. The description implies it's for thumbnails but doesn't state conditions, exclusions, or preferred scenarios. An agent must infer usage from the tool name and parameters.

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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