peek

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 peek is non-destructive ('without deleting them'), that it defaults to only new/unread messages, that it also returns delivery receipts, and that the metadata mode is ~80% smaller. This is strong behavioral context, though it does not explain whether peeking changes read state or how delivery receipts are structured.

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 front-loaded with the core behavior, then logically grouped into mode and since sections. Every sentence adds value, and the labeled sections make the details easy to scan despite the length. No filler or repetition is present.

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 there is no output schema, the description does a good job of explaining return values: full content plus payload for the default mode, and an explicit field list for metadata mode. It also mentions delivery receipts. Minor omissions such as pagination, limits, or exact delivery receipt format keep it from being fully comprehensive, but it is complete enough for an agent to call the tool correctly in most cases.

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 for everything. It explains all four parameters: mode with both allowed values and their effects, since with ISO8601 format and filter semantics, thread_id with a concrete use case, and include_read with a clear behavioral toggle. This fully covers the input schema's gaps.

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 a specific verb-resource pair: 'Read incoming messages without deleting them,' which immediately distinguishes peek as a non-destructive read operation. It also names sibling ack() and contrasts peek against acknowledgement, so an agent can tell the tools apart without opening their schemas.

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 gives clear conditional guidance: use include_read=true to see all unacknowledged messages, filter by thread_id for a specific conversation, and use ack() when done. It also recommends the metadata mode 'for defensive polling,' which gives a concrete context for choosing a mode. It does not explicitly contrast peek with dispatch or who, but enough context is present.

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