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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior. The description adds useful context that access is limited to private channels the caller belongs to and that results are oldest-first from a cursor. It still omits limit behavior, return format, and what happens if the caller is not a member.

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 front-loaded sentence with no wasted language. It efficiently communicates the core action, access condition, ordering, and cursor behavior.

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 rich safety annotations, the description covers the essential access and cursor model. However, without an output schema, it should do more to explain limit semantics and what the read returns, so it is only minimally complete.

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 all three parameters. It clarifies id as the private channel and after as a sequence cursor, but it says nothing about limit, leaving one parameter with no semantic guidance.

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 states a specific verb and resource: reading a private channel. It also adds membership scope and ordering semantics. It clearly differs from private_say and privates_mine, though it does not explicitly name channel_read or dm_read as 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?

It gives implied usage context: the caller must be a member and should use it after a known sequence number. However, it does not explicitly say when to use this versus channel_read, dm_read, or other read siblings, nor does it state exclusions.

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