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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new context: the tool only produces a string payload (it does not render a QR), the payload conforms to RFC 5870, and it is consumed by generate_qr_code — clarifying the two-step workflow. It does not say how optional altitude/uncertainty affect the emitted URI.

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?

Two sentences, zero waste, and the primary artifact is stated first with the hand-off instruction second. Every clause earns its place.

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 simple four-parameter payload builder with a fully described schema and no output schema, the description supplies what the schema cannot: what the returned value actually is (a geo: URI) and what to do with it. Nothing an agent needs in order to call 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% — latitude/longitude ranges and units for altitude/uncertainty are all documented in the schema — so the baseline of 3 applies. The description adds no syntax or formatting detail about how the four values are serialized into the geo: URI beyond what the schema already 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?

Specific verb+resource: 'Build a geo: location payload (RFC 5870)' names the exact output artifact and the standard it conforms to, and the second clause tells the agent what the payload does (opens the point in a maps app). This clearly separates it from the other qr_payload_* siblings, which produce email/sms/vcard/wifi payloads.

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 downstream guidance: 'Pass the result as `data` to generate_qr_code' tells the agent this tool only builds the string and that QR rendering is a separate step. There is no explicit exclusion (e.g. 'do not use for plain text or URLs'), so it stops short of a full when/when-not matrix.

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