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

No annotations are provided, so the description carries the full burden. It discloses that the operation is read-only (returns data) and specifies default and maximum counts. However, it does not mention message ordering (e.g., newest-first), whether the agent's own messages are included, or behavior when the channel has not been joined. These are gaps in the behavioral profile.

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 a single sentence that immediately states the action and resource, then includes key constraints (default 20, max 100). Every word earns its place, with no redundancy or filler.

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 simple read tool with one optional parameter and no output schema, the description is largely complete. It covers the purpose, the channel context, and numeric limits. Minor missing details like ordering or error conditions could enhance it, but overall it provides enough for an agent to invoke 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?

The schema description covers 100% of the parameter, and the description essentially repeats the default and max values. It adds no new semantic information beyond what the schema already provides, so a baseline score of 3 is appropriate.

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 uses the specific verb 'Return' and clearly identifies the resource as 'messages on the channel you joined'. This distinguishes it from siblings like send, read_inbox, and listen. It also states the default and maximum parameter values, making the tool's purpose unambiguous.

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 phrase 'on the channel you joined' provides clear context that the tool is for retrieving history from an active channel membership. It does not explicitly name alternatives, but given the sibling tools (e.g., send, read_inbox, listen), an agent can infer when to use this tool. No exclusions are stated.

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