slack_post_message

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

Annotations already express readOnlyHint=false and destructiveHint=true, so the description does not need to restate basic mutability. It adds valuable behavioral context: messages are sent under the bot's identity, mrkdwn is supported, thread_ts controls top-level vs reply placement, idempotency_key provides stable business-action identity, and approval_ref is used when resuming a write. No statement contradicts the annotations.

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?

The description opens with a concise one-sentence summary and then uses a structured Args list. Every line conveys a distinct detail, and the length is justified for a 9-parameter tool. It loses a point only because the Args section is somewhat mechanical and could be tightened without losing meaning.

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?

The description covers all parameters, flags required ones, and explains key mechanics like threading and idempotency. However, it does not clarify how to resolve effect values or where project_ref comes from, and there is a minor mismatch: the schema marks zero parameters as required while the description labels channel and text as required. Since an output schema exists, not describing the return value is acceptable, but an agent could still be left uncertain about governance prerequisites.

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 0%, so the description carries the full burden. The Args section compensates well by explaining all 9 parameters: channel formats (Cxxx/#/Uxxx), text formatting, thread_ts semantics, and the governance-related fields (project_id, project_ref, connector_account_ref, idempotency_key, effect, approval_ref). A few definitions are terse — 'effect' never lists allowed values, and 'project_ref' refers to an 'Exact project correlation reference' without telling how to obtain one — but it is still far better than the empty schema descriptions.

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?

The first sentence names a specific verb ('Post'), resource ('Slack channel or DM'), and identity ('under the bot's identity'), which makes the tool's core purpose clear. It does not explicitly distinguish itself from nearby siblings like slack_post_ephemeral or slack_schedule_message, so an agent gets no direct differentiation from those alternatives.

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?

There is no guidance about when to use this tool versus Slack siblings such as slack_post_ephemeral, slack_schedule_message, slack_me_message, or slack_update_message. The description only states what the tool does and gives parameter details, leaving the agent to infer usage context on its own.

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