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

Annotations already declare readOnlyHint=false, destructiveHint=true and idempotentHint=true, so the safety profile is largely covered. The description adds real context beyond that by defining patch semantics and the null-to-remove pattern for logo_url, but it never explains *why* the operation is flagged destructive (e.g. overwriting prior customization) or what the response/last-updated state looks like. Meaningful but partial supplementation of the annotations.

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 short sentences, front-loaded with the action, then the update semantics, then the one non-obvious edge case. Nothing is wasted and no sentence is redundant.

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 7-parameter, single-required-field mutation with no output schema and adequate annotations, the description covers what an agent needs to call it correctly, including patch behavior and logo removal. The main gap is the absence of any pointer to get_qr_settings for reading current values before modifying them, which would have completed the workflow picture.

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 ranges, hex formats, the enum, and the null-to-remove behavior for logo_url are all already documented in the schema. The description reinforces the omission-vs-null distinction, which is the one subtlety worth restating, but adds no new parameter meaning. Baseline 3 applies since the schema does the heavy lifting.

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+resource pair ("Save QR code customization settings for a link"), which is clearly distinct from the read-only sibling get_qr_settings. It never names an alternative tool explicitly, so it falls short of the top score for sibling differentiation, but an agent can tell what it does at a glance.

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 only implied: the phrase "Only provided fields are updated; omitted fields keep their existing values" tells the agent this is a merge-style call rather than a full replace, which is genuinely useful. There is no statement of when to prefer this over get_qr_settings/get_qr_code, no prerequisites, and no note about permissions or whether the link must already exist.

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