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

Beyond the annotations (non-readonly, non-idempotent, non-destructive), it discloses the two-step PUT-then-confirm protocol, batch atomicity, and per-plan size caps for video. It does not say what happens to a pending site if confirm_upload is never called, which is the one meaningful gap.

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 the required follow-up step. The file-type enumeration and plan-tier caps are dense but the caps carry real decision value; the enumeration is the one slice that could be trimmed.

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 multi-step upload tool with an output schema present, the description covers the protocol, the branching on site_id, and the limits an agent must respect before calling. Nothing needed to invoke it correctly is missing.

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 baseline is 3; the description earns an extra point by explaining the site_id branch and the role of subdomain/title for new sites. It does not touch the merge vs replace semantics, leaving that entirely to the schema.

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 ('Reserve presigned PUT URLs for uploading ... files directly to storage') and immediately scopes it against the inline path by naming the 1 MB limit, which separates it from write_site_files.

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 gives the two branches: omit site_id to atomically create a pending site (with subdomain/title), or provide site_id to add/replace files on an existing site. It also names the required follow-up call, confirm_upload, and the condition that selects it.

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