This record as markdown: /tools/karbassi-slack-mcp/users-set-photo.md
What users_set_photo does on Slack
AI agents use users_set_photo to create or update resources in Slack, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Slack environment.
Why users_set_photo is rated Medium
This tool modifies user profile information (photo) but does not delete or destroy data, nor does it execute arbitrary code or move money. It's reversible (the photo can be changed again), making it Write rather than Destructive. Severity is medium because unauthorized photo changes could impact user identity/trust but have limited blast radius compared to destructive or financial actions.
From the tool's definition Tool name 'users_set_photo' indicates it sets/modifies a user's photo. The server description confirms it provides 'full access to Slack' with 220 tools. Setting a photo is a reversible modification of user profile data.
Attacks that exploit this kind of access
The rule that runs users_set_photo safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Slack, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For users_set_photo, this is the rule to start with:
users_set_photo stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Slack, apply this rule, and every users_set_photo call is checked against it from then on.
Questions about users_set_photo
users_set_photo is a write tool on the Slack MCP server. It is categorised as a Write tool in the Slack MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Slack MCP server in PolicyLayer and add a rule for users_set_photo: 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 Slack. Nothing to install.
users_set_photo 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 users_set_photo 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 users_set_photo. 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.
users_set_photo is provided by the Slack MCP server (karbassi/slack-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
More on Slack, and thousands of servers like it.
This server
Across the catalogue