compare_proposal_versions
[SUPPORT] Read-only: structural diff between two proposals — most commonly two adjacent versions in a lineage chain, but works for any two existing proposal ids. Reports per-field before/after/changed for title/body/tags/status/scope_type/project_id/family_id, plus a difflib similarity ratio and ...
This record as markdown: /tools/io-github-ajc3xc-meridian/compare-proposal-versions.md
What compare_proposal_versions does on Meridian
AI agents call compare_proposal_versions to retrieve information from Meridian without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
to_proposal_id | string | Yes | Second proposal to compare (the 'b' side of each diff entry). |
from_proposal_id | string | Yes | First proposal to compare (the 'a' side of each diff entry). |
Parameters from the server's own tool schema.
Why compare_proposal_versions is rated Low
Even though compare_proposal_versions only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
The rule that runs compare_proposal_versions safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Meridian, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For compare_proposal_versions, this is the rule to start with:
compare_proposal_versions is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Meridian, apply this rule, and every compare_proposal_versions call is checked against it from then on.
Questions about compare_proposal_versions
[SUPPORT] Read-only: structural diff between two proposals — most commonly two adjacent versions in a lineage chain, but works for any two existing proposal ids. Reports per-field before/after/changed for title/body/tags/status/scope_type/project_id/family_id, plus a difflib similarity ratio and a unified diff for body specifically, plus whether the two are directly linked in the lineage graph ('adjacent') and the connecting edge(s) if so. Returns {from, to, direct_relations, adjacent, diff}. It is categorised as a Read tool in the Meridian MCP Server, which means it retrieves data without modifying state.
compare_proposal_versions accepts 2 parameters: to_proposal_id, from_proposal_id. Required: to_proposal_id, from_proposal_id. The full parameter table on this page comes from the server's own tool schema.
Register the Meridian MCP server in PolicyLayer and add a rule for compare_proposal_versions: 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 Meridian. Nothing to install.
compare_proposal_versions 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 compare_proposal_versions 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 compare_proposal_versions. 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.
compare_proposal_versions is provided by the Meridian MCP server (@meridianmcp/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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