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

With no annotations provided, the description carries the full transparency burden. It discloses that the call bypasses the source's schedule and requires both a key and owner/admin authorization, which are non-obvious behavioral constraints. It does not mention possible side effects, like pulling and storing new items, or failure modes, but it gives meaningful behavioral context beyond the bare schema.

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 a single sentence with no filler: the core purpose is front-loaded and the permission/key constraint is appended compactly. Every phrase carries useful information for selecting and invoking the tool.

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 one-parameter tool with no output schema and no annotations, the description covers the main needs: purpose, timing, prerequisite key, and required role. The only remaining gaps are a small ambiguity around what 'key' means and no mention of return values or error conditions, but these are minor for a simple trigger 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 description coverage is 100% and the sole parameter, source, is documented as 'Source slug', so the baseline for parameter semantics is appropriate. The description adds a hint that a key is needed, but does not clarify whether that key belongs to the caller or is configured on the source, and it adds no detail about slug format or where to find valid slugs.

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 names a specific action (fetch a source), the resource (source), and a clear behavioral differentiator: doing it now instead of waiting for its schedule. This distinguishes run_source from sibling read/list tools such as list_sources or feed_items, which do not trigger a source run.

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 clearly communicates when to use the tool: when an immediate source fetch is needed rather than waiting for the scheduled run. It also states prerequisites (needs a key and owner/admin permission), but it does not explicitly name sibling alternatives or say when not to use it.

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