otparse-mcp CLAUDE.md

A set of project instructions for working on otparse-mcp, a tool for parsing network-capture files. It covers the Python setup, tests, fixtures, and known limits.

In plain words
What is it for?
Setting up the project, running tests, creating PCAP test fixtures, and validating protocol fields with tshark.
Why use it?
It prevents common setup and testing mistakes and explains how to check parser results against independently verified data.

Instructions file

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add instructions/desvert/otparse-mcp/claude-md
Clone the repo
git clone --depth 1 https://github.com/desvert/otparse-mcp
Per session 806 This file is loaded in full into every session.
When invoked 806 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00806 $0.00806
Opus 5 $0.00403 $0.00403
Sonnet 5 $0.00161 $0.00161
Haiku 4.5 $0.00081 $0.00081

Measured yesterday against content hash c59d695cd442, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

otparse-mcp CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

otparse-mcp

Python environment

This project's virtual environment lives at venv/. Do not run source venv/bin/activate — it does not persist between tool calls. Instead, invoke the venv's binaries directly:

  • Run a script: venv/bin/python script.py
  • Run tests: venv/bin/pytest
  • Install a package: venv/bin/pip install <package>
  • REPL: venv/bin/python

Project setup

Install the package in editable mode before running tests or scripts — import otparse will fail otherwise, even though direct python script.py invocation works without it:

venv/bin/pip install -e .

Testing conventions

  • Fixtures live under tests/fixtures/<protocol>/ as small, hand-verified PCAP slices paired with a *_expected.json file (the parser's own verified-correct output, used as a regression baseline — not independently hand-typed).
  • Before trusting any new PCAP fixture, derive ground truth independently via raw tshark field extraction (tshark -T fields -e ...), not by reading the parser's own output. Always confirm exact field names first with tshark -G fields | grep -i <protocol> — field names are dissector-version-specific and split across layers (e.g. Modbus: mbtcp.* vs modbus.*; BACnet: bvlc.* vs bacnet.* (NPDU) vs bacapp.* (APDU)).
  • Keep fixtures small and hand-verifiable. Large/messy source PCAPs (full multi-thousand packet captures) are reserved for a separate stress-test tier, not committed as standard regression fixtures. Use editcap -r <in> <out> <frame-list> to carve small slices out of larger public captures.
  • Run the full suite with venv/bin/pytest tests/ -v.

Known limitations

  • pyshark's JSON-based dissection omits invoke_id/confirmed_service fields for BACnet Error PDUs (apdu_type=5), even though raw tshark field export has them. Documented via a runtime notes entry in parse_bacnet_pcap, not fixed.

Code conventions

  • Models are pydantic (otparse/models.py); prefer adding typed fields there over returning loosely-typed dicts.
  • Parsers use _get_attr(layer, *names) to try multiple possible pyshark attribute names — but don't guess new attribute names; introspect first with dir() or field_names on the actual pyshark layer object when uncertain.

Read the full file on GitHub · 67 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 67 lines · 806 tokens per session scan A c59d695cd442

Subscribe to this mod's changes

otparse-mcp CLAUDE.md is an instructions file published in the GitHub repository desvert/otparse-mcp (0 stars, last pushed 1mo ago), licensed MIT. It adds 806 tokens to every session, about $0.0040 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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