a2a-tck: Skill for Claude Code

.agents/skills/learn-requirement/SKILL.md

learn-requirement is a skill for Claude Code from a2aproject/a2a-tck. It costs 63 tokens per session (1,055 once invoked), scanned A, original, Apache-2.0.

A guide for understanding one A2A TCK requirement in detail. It connects a requirement ID to the protocol section, tests, and validators that check it.

In plain words
What is it for?
Use it to investigate a requirement such as CORE-SEND-001 or GRPC-ERR-001 and find the related specification text, tests, and validation code.
Why use it?
It saves time when a developer needs to understand exactly what a compatibility check means. It gathers the relevant definition and implementation details in one place.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: installed under .agents/ (shared by several agents).

This is a2aproject/a2a-tck's own configuration. It tells Claude Code how to work on a2a-tck itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything a2a-tck configures →

Reuse

Borrowing it

Nothing to install: this file belongs to a2aproject/a2a-tck. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/a2aproject/a2a-tck/main/.agents/skills/learn-requirement/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/a2aproject/a2a-tck

Made for: Claude Code.

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 learn-requirement

README.md
[![agentmods](https://agentmods.dev/badge/skills/a2aproject/a2a-tck/learn-requirement.svg)](https://agentmods.dev/skills/a2aproject/a2a-tck/learn-requirement)
Your own site
<a href="https://agentmods.dev/skills/a2aproject/a2a-tck/learn-requirement"><img src="https://agentmods.dev/badge/skills/a2aproject/a2a-tck/learn-requirement.svg" alt="Measured on agentmods" height="20"></a>
Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,055 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.
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 $0.00063 $0.01055
Opus 5 $0.00032 $0.00528
Sonnet 5 $0.00013 $0.00211
Haiku 4.5 $0.00006 $0.00105

Measured 7d ago against content hash 599135accd98, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

learn-requirement 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 7d 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.

.agents/skills/learn-requirement/SKILL.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Learn About a Requirement

Follow these steps to help the user understand a TCK requirement in depth.

Step 1: Identify the requirement

Ask the user for the requirement ID (e.g., CORE-SEND-001, GRPC-ERR-001, JSONRPC-SSE-001, HTTP_JSON-REST-001).

If the user describes a concept instead of an ID, search the requirement files to find matching requirements:

tck/requirements/core_operations.py    — CORE-*
tck/requirements/binding_grpc.py       — GRPC-*
tck/requirements/binding_jsonrpc.py    — JSONRPC-*
tck/requirements/binding_http_json.py  — HTTP_JSON-*
tck/requirements/data_model.py         — data model requirements
tck/requirements/streaming.py          — streaming requirements
tck/requirements/push_notifications.py — push notification requirements
tck/requirements/agent_card.py         — agent card requirements
tck/requirements/auth.py               — authentication requirements
tck/requirements/versioning.py         — versioning requirements
tck/requirements/interop.py            — interoperability requirements

Step 2: Read the requirement definition

Find and read the RequirementSpec entry for the requirement ID in the appropriate file under tck/requirements/.

Present the following fields to the user:

  • ID — the requirement identifier
  • Section — the spec section number
  • Title — short description
  • Level — MUST, SHOULD, or MAY
  • Description — what the requirement says
  • Operation — which A2A operation it applies to
  • Expected behavior — what a compliant implementation should do
  • Spec URL — convert the local spec_url to a GitHub link: read specification/version.json for sourceUrl, replace /tree/ with /blob/, replace trailing /specification with /docs, then append the filename and anchor from spec_url
  • Tags — categorization tags
  • Sample input — example request payload (if provided)

Step 3: Find the specification text

Read specification/specification.md and search for the section referenced by the requirement's section field. Present the relevant specification text so the user can see the normative language (MUST/SHOULD/MAY) in context.

Read the full file on GitHub · 90 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. 7d ago First seen · 90 lines · 63 tokens per session scan A 599135accd98

Subscribe to this mod's changes

learn-requirement is a skill published in the GitHub repository a2aproject/a2a-tck (49 stars, last pushed 5d ago), licensed Apache-2.0. It adds 63 tokens to every session and 1,055 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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