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

Annotations already declare readOnlyHint=true, so the safe read-only nature is established outside the description. The description adds useful behavioral context with tokenEstimate as a cost pre-screening signal and lists the metadata categories returned, though it does not detail batch response shape or error behavior.

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 tight sentences: the first states what the tool returns, the second gives the key workflow rationale, and the third covers parameter mode selection. Every sentence earns its place with no repetition or filler.

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?

For a simple, read-only stat tool, the description is nearly complete: it lists return fields, explains tokenEstimate utility, and covers both invocation modes. The main gap is that without an output schema, it does not specify the exact response structure for batch calls, but the enumerated fields mitigate this.

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 fully documents path and paths, including mutual exclusivity and the 1000-item limit. The description only restates 'Single path: pass path. Batch mode: pass paths[]', adding little beyond the structured 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 states a specific verb and resource: 'Get metadata for one or more files or directories' and enumerates the returned fields (size, type, permissions, MIME type, timestamps, tokenEstimate). This clearly distinguishes it from siblings like read (content access) and list (directory enumeration).

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?

It explicitly says to use tokenEstimate to pre-screen read cost before calling read, naming the alternative tool and the exact condition that selects stat. It also clarifies single-path vs batch-mode usage, giving practical selection guidance.

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