List files in a B2 bucket

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

With readOnlyHint=true, the annotation already signals a safe read. The description adds valuable context: it returns a page, mentions the fields, and explicitly reveals pagination via 'truncated and nextFileName'. This goes beyond the annotation. However, it doesn't clarify whether 'current files' excludes hidden files, which is relevant given sibling hide/unhide tools, so a minor gap prevents a 5.

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 three concise sentences, front-loaded with the main purpose, then output details, then pagination behavior. Every sentence contributes new information with no waste. It is appropriately sized for a tool with three parameters and a simple output structure.

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 description covers the tool's core function, return format, filtering, and pagination, which is particularly important given no output schema exists. It doesn't mention error cases or auth, but readOnlyHint covers safety. The only notable omission is clarification of 'current files' regarding hidden files, but overall the description is adequate for a listing tool.

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 100%, so the schema fully documents limit, prefix, and bucketName. The description adds minimal parameter meaning: it mentions prefix filtering and one page (which relates to limit), but these are already in the schema. Since the description doesn't clarify syntax or format beyond the schema, baseline 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 clearly states the action ('Lists'), the resource ('files in a bucket'), and the scope ('one page', 'current files'). It also distinguishes from siblings like b2_list_buckets and b2_upload_file by specifying the exact JSON fields returned. This is a specific verb+resource+scope, providing high purpose clarity.

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 context: it lists files in a bucket with optional prefix filtering and pagination. It doesn't explicitly name alternatives or exclusions, but the sibling tools are distinct (e.g., b2_hide_file, b2_upload_file), so the intended use is fairly obvious. A full 5 would require explicit 'use this instead of X' guidance, but the context is sufficient.

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