Compress chat message history using token-based trimming strategy. Removes oldest non-system messages when token count exceeds threshold while preserving system messages and recent context.
Accepts raw HTML/template content (messages[].content)
Part of the Slimcontext MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents call trim_messages to perform operations in Slimcontext. While the risk category is not fully classified, applying a rate limit gives you visibility into how often the tool is called and prevents unexpected bursts of activity from autonomous agents.
Applying a policy to trim_messages gives you an audit trail of every call an AI agent makes. Even for low-risk tools, visibility into agent behaviour helps you debug issues, optimise workflows, and maintain compliance with your organisation's security requirements.
Apply a rate limit to control usage and monitor for unexpected behaviour.
tools:
trim_messages:
rules:
- action: allow
rate_limit:
max: 60
window: 60See the full Slimcontext policy for all 2 tools.
Agents calling other-class tools like trim_messages have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Other risk category across the catalogue. The same policy patterns (rate-limit, validate) apply to each.
Compress chat message history using token-based trimming strategy. Removes oldest non-system messages when token count exceeds threshold while preserving system messages and recent context.. It is categorised as a Other tool in the Slimcontext MCP Server, which means it performs auxiliary operations.
Add a rule in your Intercept YAML policy under the tools section for trim_messages. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Slimcontext MCP server.
trim_messages is a Other tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the trim_messages rule in your Intercept 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 Intercept policy for trim_messages. 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.
trim_messages is provided by the Slimcontext MCP server (slimcontext-mcp-server). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Open source. One binary. Zero dependencies.
npx -y @policylayer/intercept