scan_folder

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

While annotations already declare readOnlyHint=true and idempotentHint=true, the description adds crucial behavioral context beyond this: it explicitly states that document contents are NOT read, only metadata (path/size/modified date). It also discloses truncation behavior (list_truncated flag, by_extension always full). These details inform an agent about side-effects and guarantees that annotations alone do not convey.

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-organized with a clear first sentence stating the core purpose, followed by a behavioral note, return format details, and usage examples. It is slightly verbose (multiple paragraphs) but every section earns its place, front-loading the key action and scoping. It could be tightened, but structure is strong.

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, output schema, multiple siblings), the description covers all essential aspects: what it returns (files array fields and by_extension counts), truncation edge-case behavior, and guidance on when to use alternatives. With an output schema present, the description need not detail return types, yet it already does so sufficiently. No critical information is missing for correct invocation.

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?

Input schema has 100% description coverage, so the baseline is 3. The description adds marginal value by reinforcing that max_files truncates the list but not the by_extension counts, which is already implied in the schema's max_files description. Since the schema documents all parameters fully, the description does not meaningfully augment parameter semantics beyond what is already structured.

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 function: it lists target files (pdf/docx/pptx/svg/png) in a folder and provides counts by extension. It explicitly distinguishes itself from siblings by stating it reads only metadata, not content, and names specific alternatives (analyze_folder, analyze_folder_structure) with conditions for their use. This makes the tool's purpose unmistakable and differentiates it from the four siblings.

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 usage guidance: use when you want to quickly check which documents exist and how many there are, with example queries. It also gives clear exclusions: do not use for content summarization (use analyze_folder) or for subfolder structure/statistics (use analyze_folder_structure). These concrete when-to-use and when-not-to-use instructions leave no ambiguity for an agent.

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