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 serac-labs/serac --skill mcp-tool-discoverygit clone --depth 1 https://github.com/serac-labs/seracWrote 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/serac-labs/serac/mcp-tool-discovery)<a href="https://agentmods.dev/skills/serac-labs/serac/mcp-tool-discovery"><img src="https://agentmods.dev/badge/skills/serac-labs/serac/mcp-tool-discovery/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/skills/serac-labs/serac/mcp-tool-discovery"><img src="https://agentmods.dev/badge/skills/serac-labs/serac/mcp-tool-discovery.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00053 | $0.05169 |
| Opus 5.5 | $0.00021 | $0.02068 |
| Sonnet 5.5 | $0.00011 | $0.01034 |
| Haiku 4.5 | $0.00005 | $0.00517 |
Grade A, and why
mcp-tool-discovery 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.
How it starts
The opening of the file, as written. The whole thing — 376 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Tool Discovery
This server registers over 440 snow_* tools across 80 domains and lists none of them. A fresh tool list
holds two meta-tools; everything else is behind tool_search. This guide is about getting from "there is
probably a tool for this" to a call that actually runs.
No exact total is quoted here, because there are two of them and they disagree:
packages/servicenow-mcp/tools.json is what the docs site publishes, the registry is what the running
server can dispatch, and nine published tools are missing from the registry (see "Nine tools you can find
in the docs but not on the server").
Cold start: two tools
A fresh tools/list on the stdio transport returns exactly this, no matter how many tools exist:
tool_search
tool_execute
That is deliberate. The server's own note puts the full catalog at roughly 71k tokens of schema against
about 2k for the two meta-tools. The index is built with every tool marked deferred, and
handlers/list-tools.ts returns only meta-tools plus whatever the current session has enabled.
The HTTP transport (the portal) does the opposite — it registers the catalog as non-deferred, so its
tools/list returns everything and nothing needs enabling. You can tell which one you are on from the
status in a tool_search result: [AVAILABLE] means the server is not gating on the enabled set at all.
The loop
// 1. Search. Found tools are enabled for this session by default.
tool_search({ query: "update-sets" })
// 2. Read the status on each hit:
// [AVAILABLE] — callable now, nothing had to be enabled
// [ENABLED] — deferred, and enabled for this session. Callable now.
// [DEFERRED] — NOT callable. Nothing was enabled; see the next section.
// 3. Execute.
tool_execute({ tool: "snow_ensure_active_update_set", args: { name: "Feature: SLA fix" } })
Pass enable: false when you only want to look — it searches without touching session state.
No session id, no tools
This is the failure that wastes an afternoon. Enablement is stored per (tenant, session). With no session
id there is nothing to attach it to, so tool_search enables nothing, every hit stays [DEFERRED], and
every call is refused:
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 · 376 lines · 53 tokens per session scan A 2013ccb3f513
mcp-tool-discovery is a skill published in the GitHub repository serac-labs/serac (78 stars, last pushed 8d ago), licensed Apache-2.0. It adds 53 tokens to every session and 5,169 once invoked, about $0.0002 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.
Other skills, from other repositories
sn-safe-write
Change ServiceNow data safely — plan first, apply only after review, verify, and know how to revert. Use whenever a create, update, upsert or delete on an instance is requested.
sn-discover
Map a ServiceNow instance into Markdown (version and counts, custom applications, per-scope tables and artefacts) with the server's own document generator. Use when asked to discover, survey, inventory or document an instance or its custom apps.
sn-drift
Find configuration drift between two ServiceNow instances or against a saved snapshot, or review what an update set will change. Use when comparing dev / test / prod, checking a promotion, or reviewing an update set.
sn-impact
Estimate the blast radius of changing a ServiceNow table, field or script — what references it and what automation runs around it. Use before renaming, deleting or changing a field, table, script include or business rule.
sn-triage
Triage a ServiceNow incident or a failing behaviour — instance health, recent errors, what automation runs on the table, and what changed on the record. Use when something is broken, slow or erroring on an instance.
sn-security
Review the security posture of a ServiceNow instance — the ACL scan, hardening properties and cross-scope access — or explain why one user can or cannot read, write, create or delete a table, record or field. Use for a security review, a hardening check, or a "why can't this user see / edit it" question.