List functions

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

Annotations declare non-read-only, non-destructive, closed-world behavior, so the safety profile is partly covered. The description adds real value by naming what is returned (runtimes, webhook URLs, usage) and the billing exposure of functions, but with no output schema it does not describe the shape of the result set, pagination, or why readOnlyHint is false for a listing operation.

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 short sentences, front-loaded with the verb and resource, and the parenthetical definition of the resource is genuinely useful rather than padding. The second sentence is a terse fragment whose referent is slightly ambiguous (functions are billed, not the listing), which keeps it from a 5.

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 no output schema, the description must carry the return-value burden, and it only sketches three returned fields while leaving the rest of the function representation, ordering, and volume undisclosed. It is adequate to recognize the tool but not complete enough to predict the response.

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?

The tool takes no parameters (empty object schema, 100% coverage), so there is nothing for the description to clarify and no parameter-level ambiguity. Baseline 4 applies for a zero-parameter tool.

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 (List) and resource (Firecracker Functions), and even explains what a Firecracker Function is (serverless-style code execution in microVMs) and what it returns (runtimes, webhook URLs, usage). It does not, however, differentiate itself from nearby siblings such as list_function_history or list_function_invocations, so an agent must infer the boundary.

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?

There is no when-to-use guidance at all: nothing says when to call this versus get_function, list_function_history, or list_function_invocations. The trailing note that functions are 'Usage-billed from the account' is billing context, not a usage rule, so the agent gets no routing help.

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