slack_get_channel_history

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

Goes well beyond the readOnly/idempotent annotations by disclosing the return shape, the has_more flag semantics, why truncation happens (small channel or Slack-imposed cap), and that user approval is required. This is exactly the kind of pitfall disclosure annotations cannot carry.

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?

Front-loaded with a short declarative sentence, then one dense sentence carrying the return contract and recovery guidance. The nested em-dash asides make it slightly hard to parse, but nothing is padding.

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?

With no output schema, the description usefully documents the return shape and the has_more contract, and notes the approval requirement. It leaves channel_id and the limit default/semantics to the schema, so it is complete enough without being exhaustive.

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 only 33% (only 'reason' is documented). The description partially compensates by implying limit behavior ('call again with a larger limit') but says nothing about channel_id or the reason parameter, leaving the low-coverage gap only partly filled. Baseline for partial coverage plus marginal added meaning is a 3.

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 (Fetch) and resource (recent messages in a Slack channel), with scope ('recent') that distinguishes it from slack_get_thread_replies and slack_search_messages. An agent can tell without opening the schema that this is a channel-scoped recent-message read.

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 concrete next-step guidance for the truncated case (call again with a larger limit or narrow the time range) rather than assuming completeness. It does not explicitly exclude or route against siblings like slack_search_messages, so it is clear context but short of explicit when-not guidance.

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