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

Goes beyond the annotations by disclosing a real failure mode (publish fails if stored content changed since the hash was obtained) and the return payload (public CDN URL). It does not address what happens when re-publishing over an existing public_path, which matters given destructiveHint=false and idempotentHint=false, but the added context is substantive.

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-loads what the tool does, then the usage exclusion, then the concurrency guard — a sensible order with no filler. Slightly redundant in re-explaining expected_content_sha256 after the schema already does so, which keeps it from a 5.

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?

An output schema exists, so return-value detail is optional, yet the description still names the URL result. For a mutation with an optimistic-concurrency guard, the key operational facts (precondition, failure behavior, when not to use) are present; only overwrite/republish semantics at an existing path are unaddressed.

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 coverage is 100%, so the baseline is 3; the description's explanation of expected_content_sha256 largely restates the schema's own wording ('from the create/update/get that produced this content'). public_path and datafile_id are covered entirely by the schema, so the description adds little parameter-level meaning 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?

Names a specific verb and resource (publish a datafile) plus the concrete outcome: a CDN path fetchable client-side. It also explicitly carves itself out from the sibling create/update/get flow and from server-side @latest datafile refs, so an agent can distinguish it from unpublish_datafile and publish_* siblings at a glance.

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?

States both the when ('Only needed for that client-side fetch') and the when-not ('NOT to bind a datafile server-side') and names the alternative mechanism that makes this tool unnecessary in that case. The precondition for the sha256 argument is also spelled out as a usage rule rather than left to inference.

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