When a tool stops at a limit or leaves something out, its result says what is missing, and the model can go back for it. The file, shell, web, source code, and Python tools come from Workcell, which also runs on its own as an MCP server.
Terminal recording · Fetch with stated limitsA real session in the demo project with gpt-6.1-sol. The network safety rules refuse a fetch of 127.0.0.1. RFC 9110 arrives cut, and the reply quotes the line [truncated: showing 49 of 492 KiB]. The RFC 8890 PDF is requested as an attachment. This model does not read PDF files, so it receives the text with a line saying that PDF attachments are disabled. The reply gives the title and a page count of 10.Open in the gallery ↗
Terminal recording · Let webfetch reach a local serverA real session in the demo project with gpt-6.1-sol. A test server listens on 127.0.0.1:8787. webfetch refuses the loopback address before any request, and the error names the entry to list under [web] in the global caudra.toml. A shell command appends allow_private_hosts = ["127.0.0.1:8787"], and the status bar shows that the [web] table reloaded at once. The next fetch still asks for approval. After a Yes, the reply checks src/pagination.ts against the fetched page and names line 29.Open in the gallery ↗
Searches that report what they withheld
A file_grep or file_glob call that reaches its bounds returns what it found and reports how much it withheld, so the model can tell a missing match from a file it never searched. Directory searches skip credential files such as .env and SSH private keys.
Search and fetch where you allow
websearch uses Exa by default, or the backends you list, such as your own SearXNG, with fallback between them. webfetch refuses private and loopback addresses unless you list a local or tailnet server under [web], and checks every redirect. A page cut at 2,000 lines or 50 KiB ends with a line that names the limit.
PDFs as text or as the file
A fetched PDF arrives as its text. In attachment mode, a model that reads PDFs receives the file itself inside the tool result, within a quarter of its context window. A resumed session attaches the saved file again.
![The fetch card for http://127.0.0.1:8080/ reads URL is blocked by network safety rules: non-public IP address is not allowed by policy: 127.0.0.1 (Loopback). Below it, RFC 9110 arrives as about 12.6k tokens, and the reply says that the text stops mid-sentence in Section 4.2.2 and quotes the line [truncated: showing 49 of 492 KiB].](/recordings/fetch.png)
