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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real behavioral context beyond the schema: the method default (recency_weighted), index-based alignment of values to labels, and the upstream-error condition for non-option questions or missing data.

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 tightly-packed sentences with zero filler; the primary purpose is front-loaded, followed by the default/alignment detail and the sibling 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?

An output schema exists so return structure needn't be described, and the description covers the remaining gaps: default method, index alignment, and error behavior. Nothing an agent needs to call this correctly 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% so the baseline is 3, but the description adds value the schema lacks: the default value for method and the index-alignment semantics linking values to labels. Only max_points is left unelaborated beyond its schema entry.

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 a precise resource ('multiple-choice option labels and the latest option-level public forecast values') for a Metaculus question or post id. It also names the sibling tool it is not (forecast_history), so an agent can distinguish this from other metaculus_* forecast 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?

Gives a concrete exclusion and alternative: 'Use metaculus_question_forecast_history for a forecast timeline instead,' plus a note that non-option questions error out. However it does not clarify when to prefer this over metaculus_question_forecasts, leaving some sibling routing to inference.

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