fetch_by_offset

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

With no annotations, the description carries the full burden of behavioral disclosure. It adds context about partition_id behavior ('offset applied to every partition') beyond the schema, and clarifies the direction of reading ('forwards'). However, it does not mention read-only status, error handling, or what happens when the offset is out of range.

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 two sentences: the first clearly states the purpose, and the second provides a targeted usage tip. It is front-loaded and free of fluff, achieving efficiency without sacrificing key information.

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?

The tool has an output schema, so return format is presumably covered. The description addresses the critical partition_id behavior for deterministic paging. However, it omits details about max_results semantics and potential edge cases like offset out of range, which may be relevant for an agent to call correctly. Overall, it is adequate but not comprehensive.

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 75% (3 of 4 params). The description adds semantic value for partition_id by explaining the offset application behavior, but provides no additional detail for max_results, which lacks a schema description. The contribution is marginal and does not fully compensate for the missing max_results semantics.

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 tool fetches messages starting at a specific offset and reads forwards. It implies a distinction from siblings like fetch_latest and fetch_by_time by focusing on offset-based retrieval, though it doesn't name them explicitly.

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 provides a useful usage tip about partition_id=-1 behavior for deterministic paging, but it does not explicitly state when to use this tool versus alternatives like fetch_latest or fetch_by_time. The guidance is more about a specific parameter behavior than tool selection.

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