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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that the data is public and that the two inputs are mutually exclusive, but says nothing about response size, pagination, or rate limits. Useful added context, not full disclosure.

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 the capability, followed by the input rule and the sibling routing. Every sentence carries a distinct, actionable fact with no padding.

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?

An output schema exists, so return values need not be explained. For a two-param read-only lookup, the description plus annotations plus schema cover purpose, routing, input exclusivity, and safety; nothing essential 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?

Schema coverage is 100% and each parameter is documented, so baseline is 3. The description adds real value beyond the schema by stating the mutual-exclusion rule ('exactly one') and the expected formats (tt... id or title URL) — the schema marks neither parameter required and encodes no oneOf, so this constraint would otherwise be invisible.

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 (fetch) and resource (IMDb release-date rows and alternate titles for a title), and explicitly names the sibling imdb_title as the alternate route. An agent can distinguish this from imdb_title and the many other imdb_title_* siblings without opening schemas.

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 an explicit when-to-use-this vs when-to-use-the-alternative rule ('Use imdb_title for general metadata instead') plus the input constraint ('Pass exactly one title id (tt...) or title URL'). Both routing and preconditions are covered.

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