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

Annotations declare readOnlyHint=false and idempotentHint=false, so the agent knows this creates something non-repeatable. The description adds genuinely useful behavior beyond that: the link is one-time, must never be replaced by in-chat key entry, and has a flat credit cost billed against the user's provider account. It stops short of stating link expiration or what is returned, which keeps it from a 5.

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 core action, then the critical behavioral rule, then the cost model. Every sentence carries information an agent needs; nothing is padded.

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?

With one parameter, no output schema, and a fully covered schema, the definition supplies the security rule and pricing that structured fields cannot. Only the link's lifecycle (expiry, single-use semantics in detail) is left implicit, a minor gap for a link-generation tool.

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 coverage is 100% and the single 'provider' parameter is already documented in the schema with a concrete example ('fal'), so the description adds no parameter-level detail. Baseline 3 applies when 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?

States a specific verb and resource ('Get a secure one-time link') and scopes it precisely to saving the user's own API key for a provider (BYOK). An agent can distinguish this from call_api or the secret_* siblings without opening the schema.

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?

Gives an explicit directive on when to use it ('Never ask the user to paste an API key into the chat — always use this link instead'), which is exactly the routing decision the agent needs. It also clarifies the cost model (flat 0.1 credits, user's provider account pays), removing a common ambiguity about who bears the cost.

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