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.
npx skills add CrestApps/CrestApps.AgentSkills --skill crestapps-core-tool-instancesgit clone --depth 1 https://github.com/CrestApps/CrestApps.AgentSkillsWrote 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/skills/crestapps/crestapps.agentskills/crestapps-core-tool-instances)<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>- NVIDIA SkillSpector pass
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 | $0.00025 | $0.00800 |
| Opus 5 | $0.00013 | $0.00400 |
| Sonnet 5 | $0.00005 | $0.00160 |
| Haiku 4.5 | $0.00003 | $0.00080 |
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.
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
IAIToolInstanceSourceand turns one configuredAIToolInstanceinto anAITool. - An instance stores its source name in
Source, its stable unique name inName, a model-facing explanation inDescription, and source-specific settings inProperties. - Register sources with
AddSource<TSource>(name, configure). The source is a keyed scopedIAIToolInstanceSourceusing the samenamestored on each instance. - Register a persistence provider such as
AddYesSqlStores()orAddEntityCoreStores()on the tool-instances builder. The feature does not choose one for you. - Use
instance.GetFunctionName()andinstance.Descriptionin a source. The generated function name uses thetool_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; }
}
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.
- 8d ago First seen · 84 lines · 25 tokens per session scan A 6ecb975eecbe
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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