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 useful behavior beyond that: the page is 'public' (no auth needed) and the parameters are mutually exclusive ('exactly one'), which the schema does not enforce. It does not discuss return format, but an output schema exists to carry that.

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, zero filler, front-loaded with the resource and scope, then the input rule, then the discovery routing. Every sentence earns its place.

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 read-only fetch tool with full schema coverage, an output schema, and safety annotations, this is nearly complete: what it fetches, how to address it, and how to find ids are all present. Minor residual ambiguity remains about what 'release-comparison metrics' concretely contains, though the output schema likely covers that.

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 individual parameter definitions are already documented and the baseline is 3. The description adds genuine meaning on top: the three params are three alternative ways to identify the same showdown and exactly one must be supplied, a mutual-exclusivity rule the schema does not encode.

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?

Specific verb (Fetch) plus a precise resource: release-comparison metrics from a Box Office Mojo showdown page. It is clearly separable from the sibling boxofficemojo_showdowns, which it explicitly routes to for discovery, and from the other boxofficemojo_* list/detail tools.

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 states the exact input contract ('pass exactly one') and names the sibling to use first for discovery ('Use boxofficemojo_showdowns to discover available comparisons'). The alternative and the selecting condition are both explicit, leaving nothing to inference.

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