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

Adds rich behavior beyond the annotations: token renewal for expired YouTube tokens, that failure forces the customer to reconnect in the Studio, and crucially that for custom RTMP/HLS/SRT (incl. LinkedIn and X) nothing is actually checked. This also reconciles with readOnlyHint=false, since renewal is a write side effect. It could note the idempotency/rate-limit angle, but the disclosure is strong.

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?

Front-loads the core purpose and return contract, then layers the platform caveats. Dense but every sentence carries decision-relevant information (especially the custom-destination warning). Slightly long, but nothing is 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?

With no output schema, the description carries the return-value burden and does so fully: 'valid true or false per destination, with a reason when it is false', plus a per-platform definition of what true means. An agent has everything needed to interpret results and call correctly.

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 destinationIds parameter is fully documented in the schema (including its source, livereacting_list_destinations). The description adds no syntax or format detail beyond that, 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 ('check that the given destinations still have a working login') and names the exact sibling it must precede ('Call this before livereacting_start_stream'). It also disambiguates what 'valid: true' means platform by platform, so the agent understands the check's true scope.

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 explicit when-to-use ('Call this before livereacting_start_stream so a failure is explained up front rather than mid-broadcast') and an implicit alternative framing: use it pre-flight rather than discovering failure mid-stream. The sibling ordering constraint is unambiguous.

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