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

With readOnlyHint/destructiveHint already declaring the safety profile, the description adds real operational context: the link expires after an hour, the user must open it in a browser and pick the file, and the same page replaces or removes an existing banner. It does not restate the read-only nature, which is the right restraint, though it says nothing about whether repeated calls produce different links (relevant given idempotentHint=false).

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 outcome, then the when-to-use rule, then the constraint and the sibling caveat, closing with a concrete example. Every sentence carries information without padding.

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?

An output schema exists, so return-value detail is unnecessary. Given one required parameter and full annotation coverage, the description supplies everything an agent needs: what the link is for, who opens it, the expiry, and where the neighbouring capability lives.

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% and the single form_id parameter is already fully documented in the schema, so the baseline is 3. The inline example format adds marginal concreteness but no semantics beyond what the schema provides.

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+resource and the exact outcome: a link the form owner opens in a browser to place an image at the top of a form. It also names what it is NOT (you cannot send the picture yourself) and routes colours to a different tool, so it is distinguishable from siblings like update_form.

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?

Explicit trigger (add/replace/remove an image, banner, header or logo), explicit alternative for a related need (colours → update_form settings.theme, which requires a paid plan, whereas a banner does not), and a clear constraint that the file lives on the user's device.

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