crestapps-core-tool-instances

crestapps-core-tool-instances is a skill for Claude Code, Codex from CrestApps/CrestApps.AgentSkills. It costs 25 tokens per session (800 once invoked), scanned A, original, MIT.

Guidance for registering configurable AI tools in CrestApps.Core, a .NET framework for building AI-enabled applications. It explains how a tool source turns saved configuration into a usable AI tool.

In plain words
What is it for?
Use it to define tool sources, register them, configure their descriptions and properties, choose a persistence provider, and generate safe function names.
Why use it?
It provides the required names, settings, registrations, and storage choices so configured tools can be created consistently. The storage provider remains a project decision.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to define tool sources, register them, configure their descriptions and properties, choose a persistence provider, and generate safe function names.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/crestapps/crestapps.agentskills/crestapps-core-tool-instances
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.

Any agent
npx skills add CrestApps/CrestApps.AgentSkills --skill crestapps-core-tool-instances
Clone the repo
git clone --depth 1 https://github.com/CrestApps/CrestApps.AgentSkills

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for crestapps-core-tool-instances

README.md
[![agentmods](https://agentmods.dev/badge/skills/crestapps/crestapps.agentskills/crestapps-core-tool-instances.svg)](https://agentmods.dev/skills/crestapps/crestapps.agentskills/crestapps-core-tool-instances)
Your own site
<a href="https://agentmods.dev/skills/crestapps/crestapps.agentskills/crestapps-core-tool-instances"><img src="https://agentmods.dev/badge/skills/crestapps/crestapps.agentskills/crestapps-core-tool-instances.svg" alt="Measured on agentmods" height="20"></a>
Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 800 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00025 $0.00800
Opus 5 $0.00013 $0.00400
Sonnet 5 $0.00005 $0.00160
Haiku 4.5 $0.00003 $0.00080

Measured 8d ago against content hash 6ecb975eecbe, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

crestapps-core-tool-instances 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 8d 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.

plugins/crestapps-core/skills/crestapps-core-tool-instances/SKILL.md · 84 lines

How it starts

The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CrestApps.Core Tool Instances - Prompt Templates

Create Configurable AI Tools

You are a CrestApps.Core expert. Generate code and guidance for developer-authored tool sources and user-configured AIToolInstance entries.

Guidelines

  • A source implements IAIToolInstanceSource and turns one configured AIToolInstance into an AITool.
  • An instance stores its source name in Source, its stable unique name in Name, a model-facing explanation in Description, and source-specific settings in Properties.
  • Register sources with AddSource<TSource>(name, configure). The source is a keyed scoped IAIToolInstanceSource using the same name stored on each instance.
  • Register a persistence provider such as AddYesSqlStores() or AddEntityCoreStores() on the tool-instances builder. The feature does not choose one for you.
  • Use instance.GetFunctionName() and instance.Description in a source. The generated function name uses the tool_instance_ prefix, provider-safe characters, a 64-character cap, and a deterministic hash when normalization is lossy.

Register a Source

builder.Services.AddCrestAppsCore(crestApps => crestApps
    .AddAISuite(ai => ai
        .AddToolInstances(toolInstances => toolInstances
            .AddYesSqlStores()
            .AddSource<MyToolInstanceSource>("my-service", options =>
            {
                options.DisplayName = new LocalizedString("my-service", "My Service");
                options.Description = new LocalizedString("my-service", "Calls the configured service.");
                options.Category = new LocalizedString("Integrations", "Integrations");
            }))));

AddToolInstances(...) registers the catalog and completion-context handler. Its useDefaultRegistry argument is true by default, which also registers ToolInstanceRegistryProvider.

Implement a Source

using CrestApps.Core;
using CrestApps.Core.AI.Tooling;
using Microsoft.Extensions.AI;

public sealed class MyToolInstanceSource : IAIToolInstanceSource
{
    public AITool CreateTool(AIToolInstance instance)
    {
        ArgumentNullException.ThrowIfNull(instance);

        var settings = instance.TryGet<MyToolSettings>(out var stored)
            ? stored
            : new MyToolSettings();

        var functionName = instance.GetFunctionName();
        var description = string.IsNullOrWhiteSpace(instance.Description)
            ? functionName
            : instance.Description;

        return CreateConfiguredTool(functionName, description, settings);
    }

    private static AITool CreateConfiguredTool(
        string functionName,
        string description,
        MyToolSettings settings)
    {
        throw new NotImplementedException();
    }
}

public sealed class MyToolSettings
{
    public string Endpoint { get; set; }
}

Read the full file on GitHub · 84 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. 8d ago First seen · 84 lines · 25 tokens per session scan A 6ecb975eecbe

Subscribe to this mod's changes

crestapps-core-tool-instances is a skill published in the GitHub repository CrestApps/CrestApps.AgentSkills (13 stars, last pushed 10d ago), licensed MIT. It adds 25 tokens to every session and 800 once invoked, about $0.0001 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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