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

Annotations already declare the safety profile (readOnlyHint=false, openWorldHint=true, destructiveHint=false), and the description adds meaningful context beyond them: all-or-nothing atomicity, per-entry validation (filename safety, extension allowlist, 10MB limit), and that it creates a single new version rather than N. This is exactly the behavioral detail annotations cannot carry.

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-loaded with the core action and cost rationale, then the validation and routing notes. It is efficient overall, though it repeats the base64 detail already stated in the schema description, which is minor redundancy.

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 two-param mutation tool with no output schema, the description covers input format, validation rules, atomicity, and sibling routing. It stops short of describing the success response or version identifier, but the key calling requirements are present.

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 both parameters (businessId, zipContent) are already documented in the schema, including that zipContent is standard base64. The description largely restates the base64 format and adds only the entry-level validation context, so the baseline 3 applies.

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?

States a specific verb and resource ('Upload a zipped bundle of files to a hosted site') and immediately differentiates itself from host_file by scope (multi-file in one call). An agent can distinguish it from all siblings without opening any schema.

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?

Explicitly says when to use it ('multi-file project ... far cheaper than N host_file calls') and names the alternative it replaces (host_file). It also routes business sites to build_website, giving a clear when-not condition.

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