capability-patch

A method for expanding an agent's abilities by changing executable code or infrastructure. It covers adding tools, exposing parameters, fixing tool implementations, and removing technical limitations.

In plain words
What is it for?
Use it to add tool methods, expose new parameters, repair incorrect tool results, and extend the actions an agent can perform.
Why use it?
It addresses problems that instructions alone cannot solve, such as a missing operation, a broken tool, or an input option the agent needs but cannot provide.

Skill for Claude CodeCodex

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 skills/microsoft/autosaddler/capability-patch
Any agent
npx skills add microsoft/AutoSaddler --skill capability-patch
Clone the repo
git clone --depth 1 https://github.com/microsoft/AutoSaddler

Made for: Claude Code, Codex.

Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,683 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00034 $0.01683
Opus 5 $0.00017 $0.00842
Sonnet 5 $0.00007 $0.00337
Haiku 4.5 $0.00003 $0.00168

Measured 2d ago against content hash 7f46ed1cdc0a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

capability-patch 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 2d 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.

src/autosaddler/v1/proposer/autosaddler/skills/capability-patch/SKILL.md · 190 lines

How it starts

The opening of the file, as written. The whole thing — 190 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Capability Patch

Overview

A capability patch expands the agent's capabilities — by adding new tool methods, exposing new parameters, fixing tool implementations, or removing infrastructure limitations. These changes let the agent do things it could not do before.

Key distinction from steering patches: A capability patch changes executable code — tool methods, parameters, implementation logic, or infrastructure. A steering patch only changes text the agent reads (docstrings, prompts, hooks) without modifying any code. The outer loop selects which skill to use based on the current phase: capability phase uses this skill, steering phase uses steering-patch.

When to Use

Based on the diagnosis results, generate a patch that resolves the identified root cause. Typical root causes addressable by capability patches:

Root Cause Category Signal Example
Missing capability No tool exists for the required action Agent needs to search emails by date range but no such tool exists
Tool bug Tool exists but produces wrong results search_contacts returns empty for valid queries due to case-sensitive matching
Insufficient parameters Tool exists but lacks needed arguments Agent needs to filter by sender but the search tool only accepts keyword
Missing agent loop logic Agent loop lacks a preprocessing step, reminder, or context-injection logic No budget reminder causes agent to exhaust iterations without wrapping up; no environment summary injection at start leaves agent unaware of available data
Infrastructure issue Infrastructure limits prevent success Agent hits the iteration budget on multi-step tasks

Workflow

Step 1: Consult History

Before writing any code, check what has been tried before:

# Full patch history: diffs, reflections, lessons (good/bad patterns)
evo-dag show history

# Per-scenario history: prior root causes and attempted fixes
evo-dag show scenario <scenario_id>

Read the full file on GitHub · 190 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. 2d ago First seen · 190 lines · 34 tokens per session scan A 7f46ed1cdc0a

Subscribe to this mod's changes

capability-patch is a skill published in the GitHub repository microsoft/AutoSaddler (150 stars, last pushed 7d ago), licensed MIT. It adds 34 tokens to every session and 1,683 once invoked, about $0.0002 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 2026-08-30.

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