agent_post_to_channel

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and does well: it discloses the write gating via an environment variable, the encryption/trust model (relay-held key, relay can read posts), and the auth identity source (local credential store). It omits failure modes beyond the env gate, rate limits, and any idempotency notes, keeping it short of a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Five short sentences, no filler, and the core action is front-loaded. Each sentence contributes a distinct fact (action, gating, encryption, readability, identity) and nothing is restated.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a three-parameter write tool with no output schema and no annotations, the description covers the operationally critical context: refusal conditions, privacy implications of relay-held keys, and acting identity. It could still say what a successful or refused call returns, but the essentials for correct invocation are present.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so channel_id, message, and reply_to are already documented in the schema. The description's note that posts are relay-readable mildly reinforces the message parameter's meaning but adds no syntax, format, or constraint beyond what the schema provides, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ("Post to a channel"), so the agent knows exactly what operation it performs. It does not, however, distinguish itself from close siblings like agent_send_message, agent_broadcast_task, or agent_read_channel, so the agent must infer which posting route applies.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives one concrete precondition — it is refused unless the human owner sets VOIDLY_MCP_RELAY_ALLOW_OPEN_WRITES=1 — which is genuinely useful guidance. But it never says when to prefer this tool over agent_send_message (DM) or agent_broadcast_task, leaving the routing decision implied.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.