read_attachment_content
Return a supported image attachment (JPEG, PNG, GIF, or WebP; maximum ${READ_ATTACHMENT_CONTENT_MAX_MIB} MiB) as one MCP image content block plus metadata-only structured content. Use this to inspect screenshots or pictures directly. For non-image, unsupported, or oversized files, call download_a...
This record as markdown: /tools/io-github-dearlordylord-huly-mcp/read-attachment-content.md
What read_attachment_content does on Huly
AI agents call read_attachment_content to retrieve information from Huly without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why read_attachment_content is rated Low
This tool retrieves and returns attachment content for viewing purposes only. It has no side effects—it does not modify, delete, or execute anything. The maximum file size limit and format restrictions further confirm this is a safe read operation. Severity is low because reading existing attachments poses minimal risk to system integrity or security, assuming access controls are properly enforced upstream.
From the tool's definition Tool description explicitly states it "Return[s] a supported image attachment" and "Use this to inspect screenshots or pictures directly." The verb "inspect" and the function of retrieving attachment content without modification confirms read-only behavior.
Attacks that exploit this kind of access
The rule that runs read_attachment_content safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Huly, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For read_attachment_content, this is the rule to start with:
read_attachment_content 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 Huly, apply this rule, and every read_attachment_content call is checked against it from then on.
Questions about read_attachment_content
Return a supported image attachment (JPEG, PNG, GIF, or WebP; maximum ${READ_ATTACHMENT_CONTENT_MAX_MIB} MiB) as one MCP image content block plus metadata-only structured content. Use this to inspect screenshots or pictures directly. For non-image, unsupported, or oversized files, call download_attachment to get a URL instead. It is categorised as a Read tool in the Huly MCP Server, which means it retrieves data without modifying state.
Register the Huly MCP server in PolicyLayer and add a rule for read_attachment_content: 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 Huly. Nothing to install.
read_attachment_content 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 read_attachment_content 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 read_attachment_content. 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.
read_attachment_content is provided by the Huly MCP server (@firfi/huly-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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