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

Annotations already declare destructiveHint=false, idempotentHint=false, and openWorldHint=true, covering the safety/mutation profile. The description adds non-obvious behavior the annotations cannot convey: verbatim property-order preservation in json, the mandatory schema binding, and the fact that a created datafile is not served until publish_datafile is called. It does not cover what happens on slug collision or validation failure, keeping it from a 5.

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?

Four tight sentences, fully front-loaded: purpose first, then the binding constraint, then a preservation guarantee, then the publish step. No filler or restated title text, and every sentence carries call-relevant information.

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 an output schema present, return values need not be explained, and the description correctly focuses on prerequisites and lifecycle instead. It covers the mandatory schema binding and the publish path, which is what an agent needs to invoke correctly; only edge-case behavior (slug conflicts, validation errors, default publish state wording) is left unstated.

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 structured fields already carry the parameter burden — that sets the baseline at 3. The description reinforces the role of schema_id (validates JSON, generates the editor) and clarifies that creation happens pre-publish, but it does not meaningfully extend semantics for slug, display_name, description, or use_latest_schema, and its property-order note for json duplicates the schema text verbatim.

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 opens with a specific verb+resource+payload ('Create a new datafile holding a JSON object'), which immediately separates it from list_datafiles, get_datafile, update_datafile, and patch_datafile. It also names adjacent lifecycle tools (publish_datafile, schema tools), so the agent can place it in the create/publish pipeline without opening other schemas.

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 states a hard prerequisite ('A datafile MUST be bound to a schema (schema_id) ... author or pick one with the schema tools first') and a clear follow-up ('Publish it with publish_datafile to serve it from the CDN'), which is actionable routing. It stops short of explicit when-not-to-use guidance (e.g. use update_datafile/patch_datafile for existing datafiles), so it is strong but not exhaustive.

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