Ops MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes the tool's interactive nature, output format ('directory listing showing folders and files with sizes and last modified times'), and includes an important behavioral constraint for the 'env' parameter ('IMPORTANT: Do NOT guess or default. Ask the user...'). However, it doesn't mention rate limits, authentication requirements, or error handling.

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 well-structured and appropriately sized. It begins with a clear purpose statement, follows with usage guidelines, provides detailed parameter explanations in a dedicated 'Args' section, and concludes with return value information. Every sentence adds value with no redundancy or fluff.

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 the tool's moderate complexity (4 parameters, 1 required), no annotations, 0% schema coverage, but with an output schema present, the description is complete. It covers purpose, usage, all parameter semantics, and output format. The output schema will handle return value details, so the description doesn't need to duplicate that information.

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?

With 0% schema description coverage, the description fully compensates by providing detailed semantic information for all parameters. It explains that 'bucket' is required, 'prefix' defaults to root with an example, 'max_results' defaults to 200, and 'env' has specific allowed values with critical usage guidance. This adds significant value beyond the bare schema.

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's purpose with specific verbs ('browse folders and files', 'list files', 'navigate', 'explore') and identifies the resource ('S3 bucket'). It distinguishes this tool from siblings like 'list_s3_buckets' (which lists buckets) and 'list_s3_recursive' (which likely lists recursively) by focusing on interactive browsing of bucket contents.

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 explicit guidance on when to use this tool ('when the user asks to see what's in an S3 bucket, list files in a folder, navigate S3, or explore any S3 path'). It also offers procedural guidance ('Start with no prefix... then drill into subfolders') and distinguishes it from alternatives by not mentioning other tools for similar tasks, implying this is the primary browsing tool.

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