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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and reach profile is covered by structured fields. The description adds no behavioral detail beyond that — no rate limits, auth or caching notes — and with an output schema present it need not explain returns. Adequate but not additive.

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 sentences, each earning its place: what is fetched, how to supply the identifier, and which sibling to use instead. The most discriminating information (the resource) is front-loaded with zero filler.

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 single-entity fetch tool with annotations covering safety and an output schema covering the return shape, the description supplies what matters: the exactly-one identifier rule and sibling routing. It is complete enough to call correctly, with only minor room to say when this title-level tool should be preferred over the release-level sibling.

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 of id/url/path is individually described, so the baseline is 3. The description goes beyond the schema by stating 'Pass exactly one' of the three identifiers — a mutual-exclusivity constraint the schema does not express (all optional, no oneOf) — which materially improves correct invocation.

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') plus the exact resources returned ('release-group and market-gross tables') for a single Box Office Mojo title. This verb+resource combination is distinct from the many sibling tools like boxofficemojo_release_group, boxofficemojo_brand, and boxofficemojo_calendar, so an agent can select it without opening a 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?

It gives clear selection context by naming the alternative ('Use boxofficemojo_release_group for the market releases in a selected release group') and specifying the input form required. It stops short of a full when/when-not treatment (e.g., whether this is the right entry point for a franchise or brand lookup), but the routing to the closest sibling is explicit.

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