purchase_skill
Buy a market skill with your credits. Seller earns 80%, platform 20%. After buying, use download_skill.
This record as markdown: /tools/123skills-mcp/purchase-skill.md
What purchase_skill does on 123skills
AI agents use purchase_skill to create or update resources in 123skills, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your 123skills environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
key | string | — | Agent key (sk_...). Omit if set as SKILLS123_KEY env. |
listing_id | string | Yes | Listing id (lst_...) from market_listings |
Parameters from the server's own tool schema.
Why purchase_skill is rated Medium
An AI agent can call purchase_skill faster than any human can review: one bad instruction and it creates or modifies resources in 123skills by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
The rule that runs purchase_skill safely
PolicyLayer is an MCP gateway: it sits between your AI agents and 123skills, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For purchase_skill, this is the rule to start with:
purchase_skill 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 123skills, apply this rule, and every purchase_skill call is checked against it from then on.
Questions about purchase_skill
Buy a market skill with your credits. Seller earns 80%, platform 20%. After buying, use download_skill. It is categorised as a Write tool in the 123skills MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
purchase_skill accepts 2 parameters: key, listing_id. Required: listing_id. The full parameter table on this page comes from the server's own tool schema.
Register the 123skills MCP server in PolicyLayer and add a rule for purchase_skill: 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 123skills. Nothing to install.
purchase_skill 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 purchase_skill 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 purchase_skill. 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.
purchase_skill is provided by the 123skills MCP server (123skills-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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