traces_listSpans

List agent traces, or read every span of one trace (GET /v1/traces/spans)

SERVERGenesis SOURCE@onesi/genesis-mcp

Low RISK CLASS

Category Read

Parameters 40 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/onesi-genesis-mcp/traces-listspans.md

WHAT IT DOES

What traces_listSpans does on Genesis

AI agents call traces_listSpans to retrieve information from Genesis 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
`limit`	integer	—	Traces per page (default 50)
`source`	string	—	Only traces exported by this source, e.g. henry
`trace_id`	string	—	32 lowercase hex characters; returns the spans of this one trace
`page_token`	string	—	next_page_token from the previous page

Parameters from the server's own tool schema.

RISK

Why traces_listSpans is rated Low

Even though traces_listSpans 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.

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs traces_listSpans safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Genesis, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For traces_listSpans, this is the rule to start with:

traces_listSpans Allowed

traces_listSpans is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "traces_listSpans": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Genesis, apply this rule, and every traces_listSpans call is checked against it from then on.

FAQ

Questions about traces_listSpans

What does the traces_listSpans tool do? +

List agent traces, or read every span of one trace (GET /v1/traces/spans). It is categorised as a Read tool in the Genesis MCP Server, which means it retrieves data without modifying state.

What parameters does traces_listSpans accept? +

traces_listSpans accepts 4 parameters: limit, source, trace_id, page_token. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on traces_listSpans? +

Register the Genesis MCP server in PolicyLayer and add a rule for traces_listSpans: 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 Genesis. Nothing to install.

What risk level is traces_listSpans? +

traces_listSpans is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit traces_listSpans? +

Yes. Add a rate_limit block to the traces_listSpans 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.

How do I block traces_listSpans completely? +

Set action: deny in the PolicyLayer policy for traces_listSpans. 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.

What MCP server provides traces_listSpans? +

traces_listSpans is provided by the Genesis MCP server (@onesi/genesis-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Genesis, and thousands of servers like it.

This server

All 1127 Genesis tools →

Across the catalogue

The MCP Attack Database →

Guides

Roll out MCP under one policy →Data exfiltration →MCP token cost →