accessibility_checkEvaluates contrast for a single foreground/background pair. For palettes or multiple colours, use accessibility_matrix instead, it replaces multiple accessibility_check calls in one response.
| Name | Required | Description | Default |
|---|---|---|---|
| hex_val | Yes | Foreground hex value | |
| background | No | Background hex (default 'FFFFFF') | FFFFFF |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotation readOnlyHint:true already establishes this is a safe read operation. Description adds that it only evaluates a single pair (scope limitation) and hints at the tool's relationship to accessibility_matrix. No additional side effects or context are disclosed, but given the annotation and simple tool, this is adequate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences, no filler. The first sentence states the primary function, the second sentence gives alternative guidance. Extremely efficient.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Tool is simple, has a readOnly annotation, an output schema, and complete parameter schema. The description covers the tool's purpose and alternative usage. The only missing info (e.g., WCAG version or return format) is likely covered by the output schema and title.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% as both hex_val and background have descriptions in the input schema. Description adds no additional parameter details beyond what schema already provides. Baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Description uses specific verb 'Evaluates' and identifies exact scope: 'contrast for a single foreground/background pair'. It also distinguishes from sibling accessibility_matrix by contrasting single pair vs palettes/multiple colours.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly states when NOT to use: 'For palettes or multiple colours, use accessibility_matrix instead', and explains benefit: 'it replaces multiple accessibility_check calls in one response'. This is clear alternative guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
With 88 tools, there is substantial overlap: colour_passport vs colour_dna vs colour_metrics vs colour_cultural_risk are explicit components of the same object; palette_concept vs palette_strict vs palette_generate vs palette_heritage overlap heavily; and four image extraction tools exist (extract_image_colours, image_palette, palette_extact, ingest_image). Although descriptions are detailed and tool_guide exists, an agent will frequently struggle to select the correct tool unambiguously.
Nearly all tools follow a consistent snake_case noun_verb or domain-prefixed pattern (colour_*, palette_*, brand_*, archive_*, project_*, accessibility_*). The naming is uniform and predictable, with no mixing of styles or verb conventions across the set.
88 tools is an extreme count for an MCP server. Even honoring the broad domain, the rubric places 50+ at the extreme end, and the high overlap between compound and individual tools suggests many could be consolidated or exposed as sub-resources rather than top-level tools.
The tool surface covers the full colour lifecycle: lookup, analysis, palettes, brand systems, accessibility, image extraction, interior design, archival research, reports, PDF generation, and project management. Workflows have clear entry points and few dead ends, and the presence of compound tools further closes integration gaps.