Given a background hex and a palette of candidate foreground colours, return them ranked by contrast ratio with WCAG grades and specific recommendations for body text, large text, and UI components.
Part of the Colour Memory server.
Free to start. No card required.
AI agents use accessibility_font to create or modify resources in Colour Memory. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call accessibility_font repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Colour Memory.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"accessibility_font": {
"limits": [
{
"counter": "accessibility_font_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Colour Memory policy for all 65 tools.
These attack patterns abuse exactly the kind of access accessibility_font gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Given a background hex and a palette of candidate foreground colours, return them ranked by contrast ratio with WCAG grades and specific recommendations for body text, large text, and UI components.. It is categorised as a Write tool in the Colour Memory MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Colour Memory MCP server in PolicyLayer and add a rule for accessibility_font: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Colour Memory. Nothing to install.
accessibility_font is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the accessibility_font rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for accessibility_font. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
accessibility_font is provided by the Colour Memory MCP server (https://colour-memory-api-production.up.railway.app/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 65 Colour Memory tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.