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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description goes beyond them by disclosing the required `read` scope (auth prerequisite) and the backend endpoint, which helps an agent predict failures rather than behavior of the call itself.

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 filler, with the core action and return shape front-loaded and the auth requirement appended as a practical footnote.

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 compensates by naming what comes back (source plus processing status with type-specific provenance), and it flags the auth scope. It stops short of describing error/404 behavior or the format of the provenance data, but nothing essential for correct invocation 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?

Only one parameter exists and schema description coverage is 100% with an example value ('src_71b0e4.'), so the schema already does the work; the description adds no additional meaning about the identifier format or constraints. Baseline 3 for a fully documented single-param schema.

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+resource ('Fetch a single source') plus the returned payload ('processing status', 'type-specific provenance'), which is enough to separate it from list_sources, get_status and get_transcript without opening a 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?

The scope ('a single source', identified by sourceId) implies the usage context, but there is no explicit when-to-use guidance or routing to alternatives such as list_sources or get_status for aggregate/batch needs. The API mapping hint adds orientation but not selection criteria.

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