Visual Studio Code is a code editor that supports editing, navigating, understanding, debugging, and extending software projects. Developers use it for the edit-build-debug cycle, and the catalogue add-ons provide skills, instructions, and agents for working within the editor.
Borrowing it
Nothing to install: this file belongs to microsoft/vscode. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/microsoft/vscode/main/.github/instructions/language-model-tool-descriptions.instructions.mdgit clone --depth 1 https://github.com/microsoft/vscodeWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/microsoft/vscode/language-model-tool-descriptions)<a href="https://agentmods.dev/instructions/microsoft/vscode/language-model-tool-descriptions"><img src="https://agentmods.dev/badge/instructions/microsoft/vscode/language-model-tool-descriptions/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/microsoft/vscode/language-model-tool-descriptions"><img src="https://agentmods.dev/badge/instructions/microsoft/vscode/language-model-tool-descriptions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00283 | $0.00283 |
| Opus 5.5 | $0.00113 | $0.00113 |
| Sonnet 5.5 | $0.00057 | $0.00057 |
| Haiku 4.5 | $0.00028 | $0.00028 |
Grade A, and why
vscode language-model-tool-descriptions.instructions.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 1mo 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.
What it actually says
Language model tool descriptions
Apply these rules only when adding or changing a model-facing tool description, such as modelDescription. They do not govern display names, user-facing messages, confirmation text, or routine schema property descriptions.
- Begin with a direct imperative statement of the tool's capability.
- When tool selection could be ambiguous, state the positive invocation criteria explicitly.
- Place exclusions for likely near-neighbor requests immediately after the positive criteria.
- Describe persistent, external, costly, or otherwise consequential side effects.
- State meaningful defaults, cross-field requirements, and prerequisite tool calls that are not obvious from the input schema.
- Put approval, cancellation, retry, repeat-call, and polling guidance last.
- Do not repeat the complete input schema in prose.
- Keep descriptions concise and scale their detail with the ambiguity and cost of incorrect selection.
- Preserve terminology and formatting conventions used by related tools.
- Reserve
MUST,ONLY,CRITICAL, and direct "Do not" language for likely, consequential misuse.
When correctness depends on specific model-facing guidance, add a focused test for the required semantic clauses. Prefer checking a small set of meaningful phrases or conditions over snapshotting the entire description. Do not test routine descriptive prose.
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.
- 1mo ago First seen · 22 lines · 283 tokens per session scan A b3168c9482c2
vscode language-model-tool-descriptions.instructions.md is an instructions file published in the GitHub repository microsoft/vscode (194,219 stars, last pushed today), licensed MIT. It adds 283 tokens to every session, about $0.0011 per session on Opus 5.5. 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 2026-08-30.
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