prowl.world
CASE STUDY 2026-10-23 6 min read

RogerThat scored 79 with a bug two runs graded 15 points apart

RogerThat's listing went 71 → 64 → 79. The last number looks like a fix. It isn't: the bug that cost points in the second run was still there in the third, 20 minutes later. This is the case study about what a score can't tell you.

RogerThat agent-readiness case study illustration
RogerThatagent-readiness71 → 64 → 79
Disclosure. RogerThat is part of The Prowl Network, the set of services we build ourselves. The runs below used the same pipeline that scores every other service in the catalog, and every number comes from the stored benchmark records.

Three runs

RunTemplateWhat was testedScore
2026-05-22platform_profileWebsite, robots.txt, llms.txt. No MCP calls.71
2026-07-21 22:29mcp_complianceinitialize 200, tools/list failed64
2026-07-21 22:49mcp_complianceinitialize 200, tools/list failed the same way79

The first run never touched the MCP server. It graded the marketing site, so its 71 says nothing about the product. Once the record declared an MCP manifest, auto-detection switched to mcp_compliance and the benchmark spoke MCP to it.

The bug

In both MCP runs, initialize returned 200. The next request, tools/list, came back with JSON-RPC error -32600: "session not initialized; call initialize first". The client had just done exactly that. To an agent this is a dead end: the server accepts the handshake and then forgets it. It cannot list tools, so it cannot call any.

Dimension (0–10)05-2207-21 22:2907-21 22:49
doc_quality767
response_parseability888
first_try_success627
error_clarity699
auth_simplicity7810
token_efficiency778
latency1098
consistency837
Overall (0–100)716479

Look at first_try_success and consistency. The 22:29 run gave them 2 and 3, which is right for a server that fails its second request. Twenty minutes later, with the same failure in the evidence, a grader gave them 7 and 7, and gave auth_simplicity a 10. The raw grade was 70, and the stored score came out 79. Only one LLM provider responded in each run (the second provider was rate-limited), so there was no second opinion to average against.

What we learned

The takeaway. Don't read a score without the evidence behind it. A 79 with a failing tools/list is worse for an agent than a 64 that reports the failure honestly. When you look at any benchmark, ours included, check the raw call results first.

Do this for your own MCP server

  1. Test the full handshake: initialize, then notifications/initialized, then tools/list, in separate HTTP requests. A server that keeps session state in memory can fail this behind a load balancer or with several workers.
  2. If your server is stateless, don't require a session. If it isn't, issue an Mcp-Session-Id on initialize and accept it on the next request.
  3. Run a free benchmark and read the per-call results, not only the overall number.
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