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

Annotations already declare readOnlyHint=false, destructiveHint=true and openWorldHint=true, so the safety bar is lower; the description still adds substantive context beyond them. It clarifies the upsert key (same link → overwrite) and explicitly reassures that 'every other document stays,' which scopes the destructive hint far better than the annotation alone, plus the sharing prerequisite and the 20-item cap.

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?

Four dense sentences with no filler, and the key upsert behavior and the sharing prerequisite are both front-loaded. The first sentence is a sentence fragment that delays the verb, costing a little clarity against an otherwise tight structure.

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 mutating tool with no output schema, the description covers what an agent needs: the upsert semantics, the scope of destruction (only the matching document changes), the sharing prerequisite, and the 20-document ceiling. Nothing essential to calling 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 description coverage is 100%, so the schema already documents all five parameters and baseline is 3. The description adds a little meaning — isSignupLink is 'the one form a new customer fills in to join' and brand ties to get_overview slugs — but it does not explain the interplay between the link as an identity key and name/whenToSend being overwritten on an existing entry.

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 names the resource (a Google Drive file the assistant can send) and the action precisely: 'Adds it, or changes the one with the same link; every other document stays,' which pins down an upsert rather than a plain create. It is distinguishable from remove_document, but the opening sentence is a noun-phrase definition rather than a verb-first statement of intent, so the action arrives slightly late.

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?

It gives a real prerequisite ('Share it with `shareEmail` from get_overview (Viewer) first') and a capacity constraint ('Up to 20'), which are genuinely useful. However, it never states when to use this versus the sibling link_document, nor what to do when the 20-document cap is already reached — usage context is implied rather than spelled out.

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