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Agent skill

Block

by xhluca in xhluca/agent-talk

Block a sender so their messages are dropped before decryption (and the relay is told to refuse their resends); re-allow one with --remove, or list blocked senders with --list.

MITAuto-check passed

Install Block

skills CLI
$ npx skills add xhluca/agent-talk --skill block -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install xhluca/agent-talk block --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/xhluca/agent-talk.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/block .claude/skills/block && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
block
GitHub stars
190
Token cost
~427 tokens
SKILL.md length
139 words
Files
1
Skills in repo
14
Repo updated
First seen
Licence
MIT

At a glance

Block a sender so their messages are dropped before decryption (and the relay is told to refuse their resends); re-allow one with --remove, or list blocked senders with --list.

  • Abusive mail from a specific sender
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Audit your block list

What it does

Block is an agent skill from xhluca/agent-talk. Block a sender so their messages are dropped before decryption (and the relay is told to refuse their resends); re-allow one with --remove, or list blocked senders with --list. Use to stop unwanted or abusive mail from a specific sender, undo a block, or audit your block list. If the sender is not specified, ask with AskUserQuestion.

Its SKILL.md is about 430 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

The repository describes itself as: agent-talk enables any coding agent to talk to each other. The licence is MIT.

When your agent uses it

  • Abusive mail from a specific sender
  • Audit your block list

Example prompts

  • “/block”

What it can do on your machine

Read from SKILL.md and the folder at commit 8a7fc4f. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Block loads about 427 tokens when it runs. Until then it costs about 86 tokens; SKILL.md has 139 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~86
When it runs · the whole SKILL.md, loaded when a task matches
~427

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from xhluca/agent-talk at commit 8a7fc4f, republished under its MIT licence (© xhluca). 139 words, ~427 tokens.

Download SKILL.mdSave it as .claude/skills/block/SKILL.md (or your agent's skills folder).
name
block
description
Block a sender so their messages are dropped before decryption (and the relay is told to refuse their resends); re-allow one with `--remove`, or list blocked senders with `--list`. Use to stop unwanted or abusive mail from a specific sender, undo a block, or audit your block list. If the sender is not specified, ask with AskUserQuestion.

block — drop a sender (--remove to re-allow, --list to audit)

retalk block <name-or-fingerprint> --dir "<user>/identity"            # block
retalk block --remove <name-or-fingerprint> --dir "<user>/identity"  # re-allow (unblock)
retalk block --list --json --dir "<user>/identity"                   # list blocked senders

Blocking drops a sender's incoming mail during receive before any decryption (so they can't consume a one-time key), and tells the relay to refuse their resends. Local to this identity. If no sender was named, use AskUserQuestion. Target the identity inline with --dir "<user>/identity".

  • --remove <name-or-fingerprint> re-allows a sender (a no-op if they aren't blocked).
  • --list --json prints the current block list (one {"fingerprint","name"} per line).

(agent-talk receives only from designated peers, so a blocked sender is already excluded from reads; block additionally tells the relay to refuse that sender's resends.)

<user> = this session's user directory — an absolute path resolved at init (e.g. ~/.agent-talk/users/alice (global) or <project>/.agent-talk/users/alice (local)). Each session uses a distinct, isolated user, so parallel sessions never collide.

Next

  • contacts — review saved peers.
  • receive — read remaining mail.

© xhluca, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/block of xhluca/agent-talk.

Open the folder on GitHubat commit 8a7fc4f

Compare with similar skills

Block next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Block compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Block this skillxhluca/agent-talk190—~427Automated safety check: PassMIT
Messages Opsaffaan-m/ECC275k1 repos~724Automated safety check: PassMIT
Block Kitopenclaw/openclaw392k—~624Automated safety check: PassMIT
Channel Message Flowsopenclaw/openclaw392k1 repos~306Automated safety check: PassMIT
Commit Message Storytellergithub/awesome-copilot40k1 repos~1.3kAutomated safety check: PassMIT
Agent Messagingdavila7/claude-code-templates32k—~807Automated safety check: PassMIT

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More from xhluca/agent-talk

All 14 skills in this repo

  • Add

    xhluca/agent-talk

    Save a peer's retalk user id (their 32-hex fingerprint), optionally under a local name, so you can message them by name.

    190 GitHub stars~1.2k tokensUpdated 28 days ago
    Auto-check passed

  • Group

    xhluca/agent-talk

    Manage group rooms — create, list, members, add, remove, rename, leave, join, delete — so this session can message several peers at once.

    190 GitHub stars~2k tokensUpdated 28 days ago
    Auto-check passed

  • History

    xhluca/agent-talk

    Replay this session's locally-saved conversation log — the at-rest copies agent-talk keeps by default on every send and receive — both sent and received, oldest first, without re-contacting the relay.

    190 GitHub stars~758 tokensUpdated 28 days ago
    Auto-check passed

  • Id

    xhluca/agent-talk

    Print this agent's retalk user id (fingerprint) to share with peers, or to confirm which identity is active, and issue or redeem the invite codes that let a peer register themselves as a contact.

    190 GitHub stars~3.5k tokensUpdated 28 days ago
    Auto-check passed

  • Receive

    xhluca/agent-talk

    Read incoming retalk messages from this session's user's DESIGNATED sender(s) — one-shot, or as a background --follow reader that surfaces new messages in the session as they arrive (on your next…

    190 GitHub stars~3.6k tokensUpdated 28 days ago
    Auto-check passed

  • Relay

    xhluca/agent-talk

    Set up, check, stop, or delete a retalk relay server (retalk-server).

    190 GitHub stars~1.5k tokensUpdated 28 days ago
    Auto-check passed

Questions about Block

What does Block do?

Block a sender so their messages are dropped before decryption (and the relay is told to refuse their resends); re-allow one with --remove, or list blocked senders with --list. Block is an agent skill from xhluca/agent-talk. Block a sender so their messages are dropped before decryption (and the relay is told to refuse their resends); re-allow one with --remove, or list blocked senders with --list.

When should I use Block?

Block fits situations like: abusive mail from a specific sender; audit your block list.

How do I install Block in Claude Code?

Run `npx skills add xhluca/agent-talk --skill block -a claude-code`. Or copy the skill folder (skills/block in xhluca/agent-talk) into .claude/skills/block in your project. Claude Code loads it when a task matches its description.

How do I install Block in Codex?

Run `npx skills add xhluca/agent-talk --skill block -a codex`. Or copy the skill folder (skills/block in xhluca/agent-talk) into .agents/skills/block in your project. Codex loads it when a task matches its description.

Can I use Block in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add xhluca/agent-talk --skill block -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/block, .gemini/skills/block, .github/skills/block and .opencode/skills/block in your project.

What does Block need to run?

SKILL.md names no scripts, command-line tools or credentials: Block is instructions for the agent only.

Does Block access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Block safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Block use?

Block is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Block use?

About 427 tokens (SKILL.md is roughly 1.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Block?

Skills that share tags, products or a category with Block: Messages Ops (affaan-m/ECC, 275k stars), Block Kit (openclaw/openclaw, 392k stars), Channel Message Flows (openclaw/openclaw, 392k stars) and Commit Message Storyteller (github/awesome-copilot, 40k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Block?

xhluca (a GitHub user) maintains it in xhluca/agent-talk, which has 190 GitHub stars. The repository holds 14 skills in this directory. The repository was last updated on September 10, 2026.

Source: xhluca/agent-talk on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.