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 agentmods add skills/monkilabs/opencastle/convexnpx skills add monkilabs/opencastle --skill convexgit clone --depth 1 https://github.com/monkilabs/opencastleWrote 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/monkilabs/opencastle/convex)<a href="https://agentmods.dev/skills/monkilabs/opencastle/convex"><img src="https://agentmods.dev/badge/skills/monkilabs/opencastle/convex.svg" alt="Measured on agentmods" 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 | $0.00067 | $0.01015 |
| Opus 5 | $0.00034 | $0.00508 |
| Sonnet 5 | $0.00013 | $0.00203 |
| Haiku 4.5 | $0.00007 | $0.00102 |
Grade A, and why
convex-database 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 5d 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 — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Convex Database
Project-specific schema, functions, and deployment details: database-config.md. Official docs: https://docs.convex.dev/
Hard limits per transaction
Exceeding one of these fails the transaction, so design against them rather than discovering them:
| Limit | Value |
|---|---|
| Query/mutation execution time | 1 second (your code only, excludes DB operations) |
| Action execution time | 10 minutes |
| Data read / written | 16 MiB each |
| Documents scanned | 32,000 — includes documents .filter() discards |
| Index ranges read | 4,096 (each db.get and db.query counts) |
| Documents written | 16,000 |
| Function return value | 16 MiB |
Batch anything larger into a cursor-based self-scheduling internalMutation:
paginate({ cursor, numItems }), then ctx.scheduler.runAfter(0, internal.x.batch, { cursor: result.continueCursor }) while !result.isDone — or use the migrations
component.
Rules That Are Easy To Get Wrong
Functions
- Public:
query/mutation/action. Internal:internalQuery/internalMutation/internalAction. All from./_generated/server. - Always set a
returnsvalidator; usereturns: v.null()when the function returns nothing (JS implicitly returnsnull). - Pass function references (
api.file.fn,internal.file.fnfrom./_generated/api) toctx.runQuery/runMutation/runAction— never the function itself.
Queries
- Do not use
.filter(). Convex's.filter()performs the same as filtering in JS — neither pushes the predicate to storage. Only.withIndex()/.withSearchIndex()reduce documents scanned. - Queries have no
.delete(): collect results, thenctx.db.delete(row._id)per row. .unique()for single-document reads.
Mutations
- Skip no-op writes: compare before
ctx.db.patch()— an unchanged write still costs invalidation, replication, and trigger execution. - Mutations are ACID transactional; use actions for external API calls and side effects.
- Breaking schema changes need widen-migrate-narrow across two deploys (widen, migrate, then narrow).
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 5d ago First seen · 79 lines · 67 tokens per session scan A 0049f396f3a3
convex-database is a skill published in the GitHub repository monkilabs/opencastle (61 stars, last pushed 7d ago), licensed MIT. It adds 67 tokens to every session and 1,015 once invoked, about $0.0003 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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