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

Annotations indicate readOnlyHint=false (write operation) and destructiveHint=false, but the description adds behavioral context by stating that a Saved Version is created before changing content. This is a meaningful safety detail not present in annotations. It also clarifies the file model follows the Fine Structure API, which informs expected behavior. No contradiction exists.

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 two sentences with no redundant content. It front-loads the core action ('Create or replace one file'), then adds a crucial behavioral note about Saved Versions, and finally provides a reference link. Every sentence earns its place, making it highly efficient.

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 write tool with 4 parameters (3 required) and no output schema, the description gives enough to understand the operation and points to external documentation for detailed API semantics. It does not mention return values or error handling, but the API link mitigates that. It also doesn't explicitly address edge cases like overwrite behavior, but 'replace' covers that. Overall, it is fairly complete for the tool's complexity.

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 parameter descriptions already exist for path, app_id, content, and file_type. The description adds value by referencing the Fine Structure app file API, which might help understand path and content semantics, but it does not elaborate on individual parameters beyond what the schema provides. Baseline 3 is appropriate given the high coverage.

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 'Create or replace one file in an app's virtual filesystem', which is a specific verb and resource. It also mentions creating a Saved Version, adding specificity. However, it does not explicitly differentiate from siblings like patch_app_file or rename_app_file, though the action is distinct enough that an agent can infer its purpose.

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 implies usage for writing files by saying 'create or replace', but it does not provide explicit guidance on when to use this tool versus alternatives like patch_app_file. There is no mention of conditions or exclusions. The reference to the API documentation suggests context but does not directly outline usage scenarios.

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