Fetch posts from Mastodon timelines (home, public, or local)
AI agents call mastodon_get_timeline to retrieve information from Mastodon MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves or queries existing timeline data without modifying, deleting, or executing any actions. It is a standard read-only information retrieval operation. The blast radius of misuse is minimal—an agent can only access posts already publicly visible on timelines, with no ability to alter data or trigger external operations.
From the tool's definition Tool description states 'Fetch posts from Mastodon timelines' - fetch is a retrieval operation with no side effects. No creation, modification, deletion, or execution capabilities are indicated.
Documented attack patterns abuse exactly the kind of access mastodon_get_timeline gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mastodon MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for mastodon_get_timeline:
{
"version": "1",
"default": "deny",
"tools": {
"mastodon_get_timeline": {}
}
}mastodon_get_timeline is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Fetch posts from Mastodon timelines (home, public, or local). It is categorised as a Read tool in the Mastodon MCP MCP Server, which means it retrieves data without modifying state.
Register the Mastodon MCP server in PolicyLayer and add a rule for mastodon_get_timeline: 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 Mastodon MCP. Nothing to install.
mastodon_get_timeline is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the mastodon_get_timeline 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 mastodon_get_timeline. 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.
mastodon_get_timeline is provided by the Mastodon MCP server (the-focus-ai/mastodon-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mastodon MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
4 Mastodon MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.