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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile needs no restatement. The description adds useful disclosure of the returned fields (license and refresh per source), which matters because no output schema exists. It stops short of saying whether the list is static, ordered, or paginated.

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?

A single sentence with no filler, front-loading the action and resource before the detail about per-source license and refresh information. 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 zero-parameter listing tool with no output schema, the description covers what the tool returns (sources with license and refresh) well enough to use it correctly. The only small gap is any hint about result size, ordering, or whether entries are stable.

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, so the baseline is 4; there is nothing the description could add about arguments. It does not falsely imply any inputs.

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 states a specific verb ('List') and resource ('sources'), and clarifies what a source is ('where the AI video tool data comes from') plus the per-item fields (license, refresh). It is clearly distinguishable from siblings like list_courses or list_places, though it does not explicitly contrast with them.

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: an agent can infer this is the tool for provenance/licensing questions, but there is no explicit statement of when to call it, when not to, or which sibling to prefer for overlapping needs. For a zero-parameter listing tool the implied usage is fairly safe, so a mid score fits.

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