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

Annotations already tell the agent this is a non-read-only, non-idempotent, non-destructive, closed-world call. The description adds real context beyond that: the link is temporary with zero data retention, the data stays in the EU, the widget is inline, and a URL is returned. It still omits link expiry duration, size limits, and what happens if the widget cannot be rendered.

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?

One dense sentence that front-loads the primary action and puts the return value immediately after. The 'AND' clause makes it slightly run-on, and parenthetical '(MCP Apps)' plus repeated 'EU' phrasing could be tightened, but no sentence is wasted.

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 no output schema, the description carries the burden of explaining the return value, and it does name upload_url and its temporary/zero-retention nature. However, it leaves out practical details an agent would need, such as link lifetime, file size limits, and fallback behavior for non-MCP-Apps clients. Adequate but with clear gaps for a tool whose only output is a transient URL.

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?

The tool takes zero parameters, so there is nothing for the description to clarify and the baseline is 4. The description correctly does not invent parameter information and instead spends its words on output and behavior.

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 uses a specific verb ('Opens') with two concrete deliverables: an inline drag-and-drop widget in MCP Apps clients and a temporary EU upload URL (upload_url). It clearly states accepted file types (PDF, DOCX, PPTX, image) and the destination (Aigine in the EU). It does not name or contrast with the siblings fetch_reviewed_document or propose_masking, but their purposes are far enough apart that confusion is unlikely.

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?

Usage is implied rather than stated: use it when a user needs to upload a document to Aigine in the EU. The phrase 'supporting chat clients (MCP Apps)' hints at an environment constraint but does not say what to do when the client does not support the widget. There are no explicit when-not conditions or references to alternatives.

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