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

Annotations already cover safety (readOnly, idempotent, non-destructive), and the description adds substantial operational context beyond them: each call is metered as one execution, a new operationId is required, short results return inline within ~2 seconds, and longer operations must be polled via operation_status/operation_output without resending. This is exactly the behavioral detail an agent needs to call safely.

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?

Front-loaded with the usage trigger, then the read-only note, required inputs, metering, and async fallback — each clause carries operational weight with little filler. Dense but not padded.

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 no output schema, the description carries the return burden and does explain the inline-vs-async result path and polling IDs. It is slightly thin on the shape of the returned entries themselves, but it covers the operationally critical return behavior.

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 already documents sessionId, operationId, path, maxDepth, and the rest. The description reiterates the sessionId/operationId contract but adds no syntax or format detail beyond the schema, making the baseline 3 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 names a specific verb and resource: listing files and folders within an approved project, which is clearly distinguishable from fs_read/fs_write/fs_search. It could be sharper about how it differs from fs_search, but the core purpose is unambiguous.

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?

"Use this when the user wants to see which files and folders an approved project contains" gives a clear triggering context, and it notes the prerequisite sessionId from execution_session_open. It does not name alternatives (e.g., fs_search) or state when not to use it.

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