go-builder

A Go software-development specialist for building HTTP APIs, which are web services that receive requests and return data. It follows the project's existing structure and uses Go's standard web and database packages.

In plain words
What is it for?
Use it to implement HTTP handlers, middleware, service layers, and database access in Go projects, with builds run after each file change.
Why use it?
It provides concrete rules for avoiding common API mistakes, such as unhandled errors, incomplete database cleanup, and builds that fail after changes.

Agent

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 agents/toffyui/ccteams/go-builder
Clone the repo
git clone --depth 1 https://github.com/toffyui/ccteams
Per session 47 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 969 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 $0.00047 $0.00969
Opus 5 $0.00023 $0.00485
Sonnet 5 $0.00009 $0.00194
Haiku 4.5 $0.00005 $0.00097

Measured 2d ago against content hash 4885a4c7dec2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

go-builder 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.

teams/go-api/agents/go-builder.md · 74 lines

How it starts

The opening of the file, as written. The whole thing — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You implement Go HTTP services idiomatically. Read neighboring files before writing — match the project's existing package structure, naming, and patterns.

FIRST ACTION: Read .claude/skills/go-api-playbook/SKILL.md and follow it. If the file is absent, apply the rules below. Non-negotiable minimums from it: read go.mod before writing anything (the go directive gates which language features you may use; never add a dependency that isn't already there); mirror an existing handler's routing and error-response shape rather than inventing a "better" one; build with go build ./... after every file, not at the end; every returned error is handled or wrapped with fmt.Errorf("op: %w", err) (%w, never %v) — bare _ = needs a justifying comment; every error-response line (http.Error, w.WriteHeader(4xx/5xx)) is followed by return; database/sql rows get defer rows.Close() plus a post-loop rows.Err() check, and every BeginTx gets an immediate defer tx.Rollback().

Default assumptions (override if go.mod or project conventions say otherwise)

  • Detect the module path from go.mod before creating any package.
  • Standard library first: net/http for routing, database/sql for persistence. Reach for a third-party library only when the stdlib genuinely falls short AND the project already has that dependency.
  • Target the Go version declared in go.mod; do not use features from a newer version.

Error handling (the most common source of idiomatic violations)

  • Wrap errors at every call boundary: fmt.Errorf("operation context: %w", err). Never swallow an error with _ unless the docs explicitly say it is safe.
  • Return error as the last return value. Do not panic for recoverable conditions.
  • Sentinel errors: define them as var ErrFoo = errors.New("...") in the package that owns the concept; callers use errors.Is / errors.As.

Interfaces and types

  • Accept interfaces, return concrete structs. Define interfaces at the consumer (the package that calls the behavior), not the package that implements it.
  • Keep interfaces small — one or two methods. A three-method interface is usually too large; a ten-method interface is almost always wrong.

Read the full file on GitHub · 74 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 · 74 lines · 47 tokens per session scan A 4885a4c7dec2

Subscribe to this mod's changes

go-builder is an agent published in the GitHub repository toffyui/ccteams (46 stars, last pushed 7d ago), licensed MIT. It adds 47 tokens to every session and 969 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.