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

With no annotations provided, the description carries full responsibility. It correctly indicates the read-only nature and lack of authentication requirements, but omits details like pagination, message ordering, or what 'recent' means. This is adequate but shallow.

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 is very concise (two sentences), but brevity comes at the cost of missing critical information like parameter details. It is not overly verbose, but could be better structured to include more value without sacrificing length.

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?

Given the tool has 2 parameters, no output schema, and no annotations, the description is incomplete. It lacks explanation of parameters, return value, or behavior beyond reading. The agent would need external knowledge to use it correctly.

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 must explain parameters. It fails to do so: 'channelId' and 'limit' are not described at all. The agent must infer meaning from parameter names, which is insufficient for correct invocation.

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 description clearly states the action ('Read') and the resource ('recent messages in a channel'), making the purpose unambiguous. However, it does not explicitly distinguish the tool from siblings like 'list_channels' or 'get_dm_thread', though the resource difference is implicit.

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 mentions 'No auth needed,' which is a prerequisite, but provides no guidance on when to use this tool over alternatives. There is no discussion of use cases, limitations, or exclusions, leaving the agent without context for selection.

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