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

Annotations already indicate readOnlyHint=false and destructiveHint=false, consistent with the description's create/update behavior. The description adds useful context beyond annotations: it explains that providing qr_id updates existing email details while preserving the short link and QR code, which is not obvious from the schema alone. It does not disclose potential side effects like generated QR image storage, but the addition of the update behavior is valuable.

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?

The description is two sentences, efficient and free of fluff. It front-loads the core purpose, then gives usage cases, then the update note. No redundant or vague filler; every sentence contributes actionable 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 output schema exists, return values need not be explained. The description covers the tool's functionality, use cases, and the update path via qr_id. It does not specify behavior when qr_id is invalid (e.g., error handling) or mention any authentication requirements, but these are likely handled elsewhere. The description is adequate for an agent to call the tool correctly for common scenarios.

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 baseline is 3. The description adds nuance beyond the schema: it clarifies that subject is required, body is optional, and CC is optional, and explains the qr_id update mechanism, which reinforces and extends the schema descriptions. This adds meaningful context, warranting a 4.

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 clearly states it creates a short link and dynamic QR code for a pre-filled email, listing the key components (recipient, subject, body, CC). It also distinguishes itself by being email-specific and explicitly lists common use cases (contact us, support, RSVPs, etc.), which differentiates it from sibling tools like save_whatsapp_link or save_app_store_link.

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 explicitly provides use cases ('Use this for contact us flows, support or quote requests, RSVPs, feedback, reservations...') and explains the update behavior via qr_id. It does not name alternative tools, but the email-specific focus makes selection clear. It could have stated when NOT to use (e.g., for WhatsApp links), but the guidance is sufficient.

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