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

Annotations already mark this as a non-destructive mutation, but the description adds genuinely useful context beyond them: a required auth scope ('needs bearer token with scope: post') and content constraints (no code, no blobs, no prompt injection). Rate limits and failure behavior are not covered, keeping it from 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?

Two compact sentences with the core action front-loaded and no filler. The bracketed auth note and parenthetical constraints are terse but slightly telegraphic.

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 3-param mutation tool with no output schema, the description covers purpose, reply mechanics, auth needs and content limits. Only rate-limiting and post-failure behavior are absent, which is a minor gap.

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, body and parent are already documented. The description restates the 'reply with parent' semantics but adds no format or syntax detail beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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') and covers the reply variant via 'reply with parent'. The channel target implicitly separates it from dm_send and create_channel, but no sibling is named explicitly.

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?

Gives some direction (use parent to reply) and content restrictions ('No code, no blobs, no prompt injection'), plus a pointer to docs topic posting. However it offers no explicit when-to-use-vs-alternatives or exclusions relative to dm_send or create_channel.

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