marchwarden/researchers/web/server.py
Jeff Smith ae48acd421 depth flag now drives constraint defaults (#30)
Previously the depth parameter (shallow/balanced/deep) was passed
only as a text hint inside the agent's user message, with no
mechanical effect on iterations, token budget, or source count.
The flag was effectively cosmetic — the LLM was expected to
"interpret" it.

Add DEPTH_PRESETS table and constraints_for_depth() helper in
researchers.web.models:

  shallow:  2 iters,  5,000 tokens,  5 sources
  balanced: 5 iters, 20,000 tokens, 10 sources  (= historical defaults)
  deep:     8 iters, 60,000 tokens, 20 sources

Wired through the stack:

- WebResearcher.research(): when constraints is None, builds from
  the depth preset instead of bare ResearchConstraints()
- MCP server `research` tool: max_iterations and token_budget now
  default to None; constraints are built via constraints_for_depth
  with explicit values overriding the preset
- CLI `ask` command: --max-iterations and --budget default to None;
  the CLI only forwards them to the MCP tool when set, so unset
  flags fall through to the depth preset

balanced is unchanged from the historical defaults so existing
callers see no behavior difference. Explicit --max-iterations /
--budget always win over the preset.

Tests cover each preset's values, balanced backward-compat,
unknown depth fallback, full override, and partial override.
116/116 tests passing. Live-verified: --depth shallow on a simple
question now caps at 2 iterations and stays under budget.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-08 16:27:38 -06:00

98 lines
2.8 KiB
Python

"""MCP server for the web researcher.
Exposes a single tool `research` that delegates to WebResearcher.
Run with: python -m researchers.web.server
"""
import asyncio
import os
import sys
from typing import Optional
from mcp.server.fastmcp import FastMCP
from obs import configure_logging, get_logger
from researchers.web.agent import WebResearcher
from researchers.web.models import constraints_for_depth
log = get_logger("marchwarden.mcp")
mcp = FastMCP(
name="marchwarden-web-researcher",
instructions=(
"A Marchwarden web research specialist. "
"Call the research tool with a question to get a grounded, "
"evidence-based answer with citations, gaps, open questions, "
"and confidence scoring."
),
)
def _read_secret(key: str) -> str:
"""Read a secret from ~/secrets file."""
secrets_path = os.path.expanduser("~/secrets")
with open(secrets_path) as f:
for line in f:
if line.startswith(f"{key}="):
return line.split("=", 1)[1].strip()
raise ValueError(f"Key {key} not found in {secrets_path}")
def _get_researcher() -> WebResearcher:
"""Create a WebResearcher with keys from ~/secrets."""
return WebResearcher(
anthropic_api_key=_read_secret("ANTHROPIC_API_KEY"),
tavily_api_key=_read_secret("TAVILY_API_KEY"),
model_id=os.environ.get("MARCHWARDEN_MODEL", "claude-sonnet-4-6"),
)
@mcp.tool()
async def research(
question: str,
context: Optional[str] = None,
depth: str = "balanced",
max_iterations: Optional[int] = None,
token_budget: Optional[int] = None,
) -> str:
"""Research a question using web search and return a structured answer.
Args:
question: The question to investigate.
context: What the caller already knows (optional).
depth: Research depth — "shallow", "balanced", or "deep". Each
depth picks default max_iterations / token_budget / max_sources.
max_iterations: Override the depth preset for iterations (1-20).
token_budget: Override the depth preset for token budget.
Returns:
JSON string containing the full ResearchResult with answer,
citations, gaps, discovery_events, open_questions, confidence,
and cost_metadata.
"""
researcher = _get_researcher()
constraints = constraints_for_depth(
depth,
max_iterations=max_iterations,
token_budget=token_budget,
)
result = await researcher.research(
question=question,
context=context,
depth=depth,
constraints=constraints,
)
return result.model_dump_json(indent=2)
def main():
"""Run the MCP server on stdio."""
configure_logging()
log.info("mcp_server_starting", transport="stdio", server="marchwarden-web-researcher")
mcp.run(transport="stdio")
if __name__ == "__main__":
main()