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

Annotations only declare destructiveHint=false, so the description must carry the rest. It adds genuinely useful platform-specific key format rules (rtmp://, rtmps://, srt://) and the required-parameter set, but says nothing about auth requirements, idempotency, error behavior, or what happens on failure.

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?

Three short sentences, front-loaded with purpose then requirements, with no filler. Slightly dense in the parenthetical format clause but every sentence carries information.

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 7-param mutation tool with minimal annotations and no output schema, the description covers the required parameters and the non-obvious key format constraint well. The optional params (url, status, include_in_schedule) are left to the schema, which is acceptable given full schema coverage.

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%, so the baseline is 3, but the description adds real meaning beyond the schema: the conditional key prefix rules keyed to platform values (custom/instagram/rumble vs customsrt). The 'max 100' note duplicates the schema but the format rules do not.

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 ('Add') and resource ('multistream destination to a stream'), which clearly separates it from siblings like list_destinations, update_destination, and remove_destination. An agent can identify the operation without opening the 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?

No when-to-use or when-not guidance, and no alternatives named. It implies creation context via 'Required:' and the mirrored POST endpoint, but an agent gets no help choosing between this and update_destination or when adding a destination is appropriate.

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