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

Annotations declare a non-read-only, non-idempotent, open-world write; the description adds genuinely new context by stating the authorization requirement ('needs a key; owner or admin'). It does not disclose what a call costs or that repeated calls each trigger a separate run, which matters given idempotentHint=false.

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?

One sentence, front-loaded with the action and the motivation, with the permission constraint in parentheses. Nothing wasted.

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 trigger tool with no output schema and clear annotations, this covers the essentials: what it does, why, and who can call it. What happens after the call (does it return a run id, or is it fire-and-forget?) is left unstated and would be useful given there is no output schema.

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 coverage is 100% and the single parameter is well documented with an example slug and a pointer to list_sources. The description adds no additional meaning beyond the schema, so the baseline 3 applies.

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 and resource ('Fetch a source') plus the key differentiator — immediate execution rather than waiting for the schedule. An agent can distinguish it from list_sources or add_source, though the description never names those siblings directly (only the schema does).

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?

Gives a clear trigger condition: use this when you want the source fetched immediately rather than on its schedule. It stops short of stating when not to use it (e.g., repeated calls, quota limits) or naming alternatives explicitly.

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