read_channel_history

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

Annotations provide readOnlyHint=true, which covers the safety profile. The description adds the public-channel constraint beyond the schema. It doesn't disclose pagination behavior, rate limits, or whether the tool excludes the around_ts message or includes messages before it, but with readOnlyHint already declared, the bar is lower; the description adds modest value.

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 compact with clear parameter listing and useful details (public-only constraint, limit bounds, around_ts semantics). Slightly verbose with the 'Args:' formatting but well-organized and front-loaded with the primary purpose. No wasted sentences.

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 an output schema present, return-value documentation isn't needed. The description covers the tool's read-only nature, public-channel constraint, parameter semantics, and alternative mode (around timestamp). For a moderately complex tool with 3 parameters, this is reasonably complete, though it could mention pagination limits more explicitly.

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 compensate. It explains channel (id or #name), limit (1-100, default 30), and around_ts (returns up to and including that timestamp). This adds genuine meaning beyond the bare schema, which has no descriptions. However, it doesn't elaborate on the exact format of channel ids or timestamp format, so it's adequate but not exhaustive.

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+resource: 'Read recent messages from a PUBLIC channel, or messages around a timestamp.' This clearly distinguishes it from sibling tools like send_message (write) and search_messages (query across channels). However, it doesn't explicitly differentiate from read_thread, which is a closely related read tool.

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 explicitly states channels must be public ('Must be a public channel'), which is a critical constraint. It also clarifies the around_ts behavior for reading context at a specific point. However, it doesn't explicitly say 'use search_messages instead when looking across channels,' so alternatives aren't named.

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