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MCP server: get_attributes tool always fails for named attributes - TypeError: get_attribute() got an unexpected keyword argument 'timeout' #4542
Description
Environment
- OS: Linux (Ubuntu, x86_64)
- SeleniumBase version: 4.54.13, and verified still present in the 4.56.5 wheel on PyPI
- Python: 3.10
- Browser: Google Chrome 152 (Pure CDP Mode)
- Affected component:
mcp_servers/server.py(SeleniumBase MCP server) +seleniumbase/core/sb_cdp.py
Summary
The get_attributes MCP tool always fails when a named attribute is requested — even when the MCP client omits timeout, because the server passes its own default (timeout=5) through to CDPMethods.get_attribute(), which does not accept a timeout parameter.
Repro
Via the MCP server (get_attributes with selector + attribute, e.g. attribute="href" on a link):
Error in get_attributes: TypeError - CDPMethods.get_attribute() got an unexpected keyword argument 'timeout'
Equivalent direct CDP Mode repro:
from seleniumbase import SB
with SB(uc=True, headless=True) as sb:
sb.cdp.open_url("https://example.com")
print(sb.cdp.get_attribute("h1", "innerText", timeout=5))
# TypeError: CDPMethods.get_attribute() got an unexpected keyword argument 'timeout'Root cause
mcp_servers/server.py, get_attributes tool (line 679 in 4.56.5; identical in 4.54.13):
if attribute:
return sb.get_attribute(selector, attribute, timeout=timeout)
return sb.get_element_attributes(selector, timeout=timeout)But seleniumbase/core/sb_cdp.py:
def get_attribute(self, selector, attribute):
# line 1908 in 4.54.13 / 1934 in 4.56.5 — no `timeout` parameterThe all-attributes path works fine because get_element_attributes() does accept timeout.
Suggested fix
Drop the unsupported kwarg:
return sb.get_attribute(selector, attribute)or preserve the documented timeout semantics by waiting for the element first:
if attribute:
sb.find_element(selector, timeout=timeout)
return sb.get_attribute(selector, attribute)Happy to open a PR if helpful.
Activity
mdmintz commentedon Nov 1, 2026
Thanks for reporting this. Will be fixed in the next release.
Note that your reproduction steps are incorrect. The MCP server uses Pure CDP Mode (
sb_cdp).The proper code to reproduce the issue directly should look like this:
SynthLuvr commentedon Nov 1, 2026
Thanks @mdmintz for the quick response and the correction — you're right that
sb_cdp.Chrome()is the canonical Pure CDP Mode entry point. I confirmed your form reproduces it exactly:(The signature mismatch is in
CDPMethods.get_attribute()itself, so it reproduces from either entry point, but yours is the proper direct repro.) Looking forward to the next release — I'll validate the fix against it and report back.mdmintz commentedon Nov 3, 2026
This was resolved in
4.57.0- https://github.com/seleniumbase/SeleniumBase/releases/tag/v4.57.0