John's Essentials

generate_favicon

Favicon Generator — Generate a favicon set (ico + png sizes) from a source image, with optional rounded corners. This is the tiny icon a browser shows in the tab, beside a bookmark, and on a phone home screen — without one, visitors see a blank page symbol next to your site's name. [category: generate]

Input Schema

TableJSON Schema

Name	Required	Description	Default
`file`	Yes	Source image (PNG, SVG, JPG — max 20MB)
`background`	No	Fill behind a logo that is not square. None leaves it see-through, which suits both light and dark browser tabs. A hex colour such as #1a1a1a is also accepted; anything we do not recognise is treated as see-through.	none
`includeIco`	No	Also generate favicon.ico.
`borderRadius`	No	Rounded-corner radius as a percent (0-50).

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 23, 2026
- addedInput schema / properties / borderRadius / x-ui
```
Added value: +{
+  "unit": "%"
+}
```

Changed1 schema field changedSep 11, 2026

addedInput schema / properties / background

Added value: +{
+  "default": "none",
+  "description": "Fill behind a logo that is not square. None leaves it see-through, which suits both light and dark browser tabs. A hex colour such as #1a1a1a is also accepted; anything we do not recognise is treated as see-through.",
+  "enum": [
+    "none",
+    "white",
+    "black",
+    "gray",
+    "silver",
+    "red",
+    "green",
+    "blue",
+    "yellow",
+    "orange",
+    "purple",
+    "pink",
+    "brown",
+    "navy",
+    "teal",
+    "cyan",
+    "magenta"
+  ],
+  "type": "string",
+  "x-ui": {
+    "labels": {
+      "none": "See-through"
+    }
+  }
+}

First observedSep 5, 2026

TDQS

B3.2/5.0

Behavior2/5

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

Annotations are minimal (readOnlyHint=false, destructiveHint=false), so the description carries most of the transparency burden. It discloses the output format (ico + png) but not how the generated files are delivered, whether generation creates side effects, or what happens if the source image is invalid. Significant behavioral gaps remain.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The core action is front-loaded and the overall entry is short. The second sentence explaining what a favicon is and the blank-page consequence is contextual padding rather than invocation guidance, but it does not bloat the description enough to hurt usability.

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 simple 4-parameter tool, the description plus fully documented schema cover inputs and the output format reasonably well. However, there is no output schema and no mention of how the generated favicon set is returned or stored, leaving the result of the call somewhat underspecified.

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%, and every parameter already has a meaningful description, default, and constraints. The description adds only high-level phrasing like 'optional rounded corners' and 'from a source image', which mirrors existing schema fields. It does not meaningfully extend parameter understanding.

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?

States a specific verb ('Generate'), a precise resource ('favicon set (ico + png sizes)'), and the source ('from a source image'). The operation is clearly distinct from the many sibling generate_* tools. No ambiguity about what this tool produces.

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 explicit when-to-use guidance or alternative comparisons are given. The favicon explanation implies a use case, but it never tells an agent when to choose this over related image/generation tools. Nothing about exclusions or prerequisites is provided.

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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