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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false, and destructiveHint=false. The description adds genuinely useful non-schema context: it is a real-time streaming endpoint, it is a POST, and it costs 10 credits (Tier 1). It does not, however, explain what streaming implies (connection handling, delivery cadence, how to consume the stream), which is the key behavioral unknown for this tool class.

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?

Very compact and front-loaded: the payload sentence comes first, followed by bracketed metadata that is easy to scan. Nothing is wasted, though the terse style leaves behavioral gaps rather than being merely economical.

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 described here. The essentials (required coords, cost, streaming group) are present, but for a real-time streaming tool with readOnlyHint=false there is no explanation of the streaming lifecycle or connection behavior, leaving the definition minimally adequate.

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 60%: fields, precision, and timezoneOffset are documented in the schema, while latitude and longitude carry no descriptions. The description only restates that latitude and longitude are required, which the schema already marks as required, so it adds little parameter-level value. Baseline 3 fits given the moderate coverage and the self-evident nature of lat/long.

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 resource (sun events) with a scope qualifier (today + tomorrow), and the tool name plus endpoint make the sunrise/sunset purpose unmistakable. It does not explicitly differentiate from sibling stream tools like lunar_phase or ingress, but the resource is distinct enough that an agent can tell them apart.

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?

There is no when-to-use vs alternative guidance. The bracket notes list group, endpoint, requirements, and cost, but never say when an agent should pick this stream over another stream tool or a webhook equivalent. Usage is only implied by the name.

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