katto_list_sources

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

The annotation already declares readOnlyHint and destructiveHint, so the description's statement 'Read-only' adds no new behavioral information. It does mention that each platform has an example URL, which slightly clarifies the output, but this is minor compared to what is already disclosed by annotations.

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 concise, consisting of two short sentences that efficiently convey the tool's purpose and usage. It avoids unnecessary detail and is well-structured for quick comprehension.

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?

The description provides sufficient context: it explains what the tool returns (platforms with example URLs), its read-only nature, and its relationship to katto_create_clip_job. While it does not enumerate the specific platforms or the response schema, this level of detail is adequate for an agent to understand when and why to call the 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?

The tool has zero parameters, and the schema coverage is complete (no params to describe). Per the baseline rule for 0 params, a score of 4 is appropriate, as there is no parameter information that the description needs to supplement.

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 that the tool lists video platforms supported by Katto, each with an example URL, and explicitly distinguishes it from other tools by mentioning its read-only nature and its role in confirming URL support before calling katto_create_clip_job.

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 provides explicit guidance on when to use this tool: to confirm a URL is supported before invoking katto_create_clip_job. This makes the usage context unambiguous and actionable for an agent.

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