chembl-mcp-server: Instructions file for Claude Code

AGENTS.md

chembl-mcp-server AGENTS.md is an instructions file for Claude Code, Codex, OpenCode from cyanheads/chembl-mcp-server. It costs 7,121 tokens per session, scanned A, a copy of obsidian-mcp-server AGENTS.md, Apache-2.0.

A project-specific instruction guide for chembl-mcp-server, an MCP server that provides read-only drug-discovery data from ChEMBL, a public database of compounds, targets, and bioactivity results.

In plain words
What is it for?
Use it when developing, testing, or extending tools that search molecules and targets or retrieve drug bioactivity, mechanisms, and indications.
Why use it?
It explains the server's tools, development rules, framework conventions, and required runtime versions before you change the code.

Instructions file for Claude CodeCodexOpenCode

Written for Claude Code and Codex and OpenCode: Claude Code plugin machinery, but also the file is AGENTS.md. Also seen: reads .claude/ paths; mentions CLAUDE.md; mentions subagents.

This is cyanheads/chembl-mcp-server's own configuration. It tells Claude Code, Codex and OpenCode how to work on chembl-mcp-server itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything chembl-mcp-server configures →

Reuse

Borrowing it

Nothing to install: this file belongs to cyanheads/chembl-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/cyanheads/chembl-mcp-server/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/cyanheads/chembl-mcp-server

Made for: Claude Code, Codex, OpenCode.

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README.md
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<a href="https://agentmods.dev/instructions/cyanheads/chembl-mcp-server/agents-md"><img src="https://agentmods.dev/badge/instructions/cyanheads/chembl-mcp-server/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 7,121 This file is loaded in full into every session.
When invoked 7,121 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 77% copy Near-identical to another mod 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 5.1 $0.07121 $0.07121
Opus 5 $0.03560 $0.03560
Sonnet 5 $0.01424 $0.01424
Haiku 4.5 $0.00712 $0.00712

Measured 6d ago against content hash 3eb9f11b9a76, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

chembl-mcp-server AGENTS.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 6d ago.

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.

Origin

This is a copy

77% identical to obsidian-mcp-server AGENTS.md — 336 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

AGENTS.md · 415 lines

How it starts

The opening of the file, as written. The whole thing — 415 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Developer Protocol

Server: chembl-mcp-server Version: 0.2.4 Framework: @cyanheads/mcp-ts-core ^0.12.3 Engines: Bun ≥1.3.0, Node ≥24.0.0 MCP SDK: @modelcontextprotocol/server ^2.0.0 Zod: ^4.4.3

Read the framework docs first: node_modules/@cyanheads/mcp-ts-core/CLAUDE.md contains the full API reference — builders, Context, error codes, exports, patterns. This file covers server-specific conventions only.


Server surface

ChEMBL drug-discovery data over the EBI REST API (https://www.ebi.ac.uk/chembl/api/data) — keyless, read-only. The curated compound ↔ target ↔ bioactivity link, plus drug mechanisms and indications.

Tools (src/mcp-server/tools/definitions/):

Tool Purpose
chembl_search_molecules Discovery entry point — find compounds by name / ChEMBL ID / InChIKey, or structure search (exact / similarity / substructure) from a SMILES
chembl_search_targets Resolve a protein / gene / UniProt accession to the ChEMBL target ID chembl_get_bioactivities needs
chembl_get_bioactivities Flagship compound↔target bridge — bioactivity measurements for a molecule, a target, or both (which narrows to that compound–target pair); potency_view picks the measurements with a derivable pchembl_value (default) or exactly those without one; large sets spill to a per-view DataCanvas table SQL'd via chembl_dataframe_query
chembl_get_drug_info Drug pharmacology — mechanism(s) of action, target(s), first-approval year, clinical indications
chembl_get_assay Assay provenance behind a bioactivity row — type, target, organism, 1–9 confidence score
chembl_dataframe_query Read-only SQL SELECT over the spilled bioactivity rows (canvas)
chembl_dataframe_describe List tables/columns staged on a canvas before querying
chembl_dataframe_drop Drop a staged table early. Opt-in behind CHEMBL_DATAFRAME_DROP_ENABLED; wrapped in disabledTool() when off, so it carries the enable hint in the manifest while staying absent from tools/list

Read the full file on GitHub · 415 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. 6d ago First seen · 415 lines · 7,121 tokens per session scan A 3eb9f11b9a76

Subscribe to this mod's changes

chembl-mcp-server AGENTS.md is an instructions file published in the GitHub repository cyanheads/chembl-mcp-server (1 stars, last pushed 12d ago), licensed Apache-2.0. It adds 7,121 tokens to every session, about $0.0356 per session on Opus 5. A static security scan graded it A with 0 findings. It is 77% identical to obsidian-mcp-server AGENTS.md, differing in 336 lines, and is treated as a copy.

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