cwms-tools

Read-only, agent-friendly tools for the U.S. Army Corps of Engineers' CWMS Data API. cwms-tools wraps the official cwms-python client with two surfaces that share one behavioral core:

• an MCP server for agent runtimes such as Claude Code, Codex, and custom MCP clients
• a non-interactive CLI with compact JSON output, stable exit codes, and a machine-readable schema

The goal is simple: let agents answer common hydrologic questions with one task call instead of a brittle chain of raw API lookups.

What It Does

• Resolves natural place names to canonical CWMS locations, with ghost-location filtering and co-located sensor hints.
• Describes a place in one call: location record, project metadata when available, published parameters, publishers, and latest data timestamp.
• Reads the latest value or bounded history for CWMS time series parameters.
• Optionally classifies the latest value against CWMS Location Levels when callers opt in with --with-status or with_status=true.
• Browses one office's catalog by state or bounding box.
• Finds publishers for a parameter across cached or explicitly requested offices.
• Serves a bundled CWMS orientation document as MCP resources so agents can load background material selectively.

Install

uv add cwms-tools
# or:  pipx install cwms-tools

To run from a checkout instead:

git clone https://github.com/briandconnelly/cwms-tools.git
cd cwms-tools
uv sync
uv run cwms-tools --help

CLI Quick Start

The CLI is designed for non-interactive callers. When stdout is not a TTY, machine mode is enabled automatically: compact JSON on stdout, diagnostics on stderr, no color, no prompts, and no progress UI. You can force that profile with --machine or --json.

# Inspect the resolved session and upstream API root.
uv run cwms-tools whoami

# Print the command tree, output classes, exit codes, environment inputs,
# MCP tools, and MCP resources as a stable machine-readable contract.
uv run cwms-tools schema

# Print a SHA-256 fingerprint over the agent-visible capability surface.
uv run cwms-tools fingerprint

# Resolve a place name to ranked CWMS locations.
uv run cwms-tools place search "Fort Peck" --office NWDM

# Describe one place: location, project metadata, parameters, publishers,
# freshness, and partial-result flags.
uv run cwms-tools place describe NWDM/FTPK

# List parameters published at a place.
uv run cwms-tools place parameters NWDM/FTPK

# Read the latest elevation value. Status lookup is skipped by default because
# CWMS Location Levels calls can be slow.
uv run cwms-tools value get NWDM/FTPK/Elev

# Opt in to threshold classification when status context matters.
uv run cwms-tools value get NWDM/FTPK/Elev --with-status

# Read a bounded history window.
uv run cwms-tools value history NWDM/FTPK/Elev \
  --begin 2026-05-16T00:00:00Z \
  --end 2026-05-17T00:00:00Z

# Browse an office catalog by state.
uv run cwms-tools region browse --office SWT --state OK

# Page through a large browse result. Pass the prior response's `next_cursor`
# value as --cursor to continue without re-issuing the same search.
uv run cwms-tools region browse --office NWDM --cursor <next_cursor>

# Find publishers reporting a parameter in selected offices.
uv run cwms-tools publisher for-parameter Elev --office NWDM --office SWT

Pagination works the same way for place search:

RESULT=$(uv run cwms-tools --machine place search "Reservoir" --office NWDM)
CURSOR=$(echo "$RESULT" | python -c "import sys,json; d=json.load(sys.stdin); print(d.get('next_cursor',''))")
# If CURSOR is non-empty, there are more pages:
uv run cwms-tools --machine place search "Reservoir" --office NWDM --cursor "$CURSOR"

value history sets next_begin in the response when the upstream truncates at 300 000 points. Pass that value as --begin on the next call to continue the window without overlap or gap:

uv run cwms-tools --machine value history NWDM/FTPK/Elev \
  --begin 2025-01-01T00:00:00Z --end 2025-12-31T23:59:59Z
# If response.next_begin is set, continue from there:
uv run cwms-tools --machine value history NWDM/FTPK/Elev \
  --begin <next_begin> --end 2025-12-31T23:59:59Z

Useful global flags:

• --machine / --json: compact structured output for agents and scripts.
• --no-cache: bypass the on-disk catalog cache for one invocation.
• --isolated: bypass cache and ignore CWMS_TOOLS_* environment variables.
• --version: print the installed cwms-tools version.

Exit codes are part of the CLI contract:

MCP Quick Start

Use stdio for local agent runtimes:

uv run cwms-tools mcp serve --transport stdio

Use streamable HTTP for shared or remote deployment:

uv run cwms-tools mcp serve --transport streamable-http --host 127.0.0.1 --port 8765

Claude Code config example:

{
  "mcpServers": {
    "cwms-tools": {
      "command": "uv",
      "args": ["run", "cwms-tools", "mcp", "serve", "--transport", "stdio"]
    }
  }
}

The MCP server exposes task-level tools rather than raw endpoint mirrors:

Resources:

• cwms://capabilities: server version, fingerprint, tools, and resources.
• cwms://overview: index of bundled CWMS overview sections.
• cwms://overview/{section_id}{?detail}: summary or full section body.
• cwms://overview/{section_id}/chunk/{chunk_id}: one large-section chunk.

Configuration

cwms-tools works anonymously by default. Environment variables are optional:

Inspect the resolved configuration without making a data call:

uv run cwms-tools env
uv run cwms-tools config show --resolved

CWMS Notes

CWMS is USACE's Corps Water Management System: the operational data platform for federal reservoirs, flood-control dams, navigation locks, hydropower projects, and environmental monitoring stations.

Two upstream data-shape issues come up often:

• Ghost records. Some catalog locations do not publish time-series data. Search and browse responses expose parameter_count, parameters, and data_at repair hints so agents can move to the data-bearing sibling.
• Northwestern Division stubs. NWO, NWK, NWS, NWP, and NWW are near-empty CDA stubs. Use NWDM for Missouri River data and NWDP for Pacific Northwest data. Error envelopes include repair hints when a stub is targeted.

Upstream Etiquette

The CWMS Data API is a shared public service. cwms-tools identifies itself with a descriptive User-Agent, caps concurrent requests, avoids background scans, and does not cache live time-series values. The underlying cwms-python client retries throttled requests with backoff; a 429 that still surfaces is returned as a rate_limited error whose retry_after_ms echoes the upstream Retry-After header so callers can back off. If you operate CDA and see problematic traffic from this client, please open an issue at https://github.com/briandconnelly/cwms-tools/issues.

Development

uv sync
uv run prek run --all-files
uv run pytest --cov=cwms_tools
uv run ty check

The test suite uses unit tests and mocked CDA responses. Live CDA integration tests are marked integration and are skipped unless explicitly selected.

Before opening a substantial PR, please open an issue to discuss the intended change. The package is published on PyPI but still pre-1.0, so the CLI/MCP schema contract may change between minor releases — it is the main compatibility surface, and the capability fingerprint (cwms-tools fingerprint) moves whenever it changes.

License

MIT