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

Annotations are all false, so the description carries the full burden of behavioral disclosure. It reveals the multi-step nature (PUT each file, then confirm_upload), the atomic batch semantics for new sites, the mode-dependent behavior (merge vs replace), and the fact that a new site is created as 'pending.' This goes well beyond the annotations and gives an agent a realistic model of the operation's side effects.

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?

Three sentences, no filler. The core purpose is front-loaded, the two usage branches are clearly separated, and the required follow-up action is stated at the end. Every sentence contributes essential 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?

Given the tool's complexity (multi-step upload, new vs existing site, merge/replace modes), the description covers the full workflow, the atomicity guarantee, and the dependency on confirm_upload. An output schema exists, so return values need not be described. No critical operational detail 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 the baseline is 3. The description adds value by explaining the conditional semantics of site_id ('Omit when creating a new site... Provide to add or replace files'), clarifying that subdomain/title are only used for new sites, and noting that a new site always publishes exactly the batch. These relationships are not fully captured in the schema's per-field descriptions.

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 and resource: 'Reserve presigned PUT URLs for uploading one or more large or binary files directly to storage.' It clearly distinguishes the tool from siblings by mentioning the 1 MB inline limit bypass and the follow-up confirm_upload step, so an agent can tell it apart from write_site_files or replace_site_files without inspecting 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?

The description gives clear context for when to use the tool: for large/binary files exceeding the inline limit, and it explains the two distinct usage branches (omit site_id for new site, provide site_id for existing site). It does not explicitly name alternative tools for small files, but the 'bypassing the 1 MB inline limit' phrasing implies the alternative, and the workflow with confirm_upload is explicit.

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