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

With no annotations, the description carries the full burden. It usefully discloses auth requirements (key must permit the operation), quota and key-budget accounting, and a retry prohibition. It omits whether calculations are read-only/no-side-effect, what a failure or quota-exhaustion response looks like, and whether calls are metered per-route, leaving meaningful gaps for a gateway to 77 operations.

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 core action, and every sentence carries operational substance (auth, quota, no-retry). Minor deduction because the quota/budget sentence is somewhat dense while higher-value context, such as what a call returns, is absent.

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?

No output schema exists, yet the description says nothing about the shape or variability of results across 77 operations. For a complex multi-operation gateway with nested input and no annotations, this is adequate but leaves the agent guessing about response form and failure modes.

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 description coverage is 100% and the schema text is unusually rich (date ranges, calendar conventions, the /api/astro/ prefix, redirection to the symbolic tool). The description adds nothing about `operation` or `input`, so baseline 3 applies.

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 and resource: 'Run one live Cosmic Ephemeris calculation.' An agent can tell this is the live-calculation gateway. It does not itself distinguish the tool from the sibling cosmicephemeris_symbolic; that separation lives only in the input schema, so sibling differentiation is missing from the description.

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?

Provides operational guidance ('the supplied API key must permit the selected operation', 'do not automatically retry failures') but never says when to choose this tool over cosmicephemeris_symbolic or what to do if the key is rejected. Usage context is implied rather than stated as an explicit when/when-not rule.

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