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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds real context beyond that: the content is a fixed list with stable ids (relevant for downstream referencing), exact coverage by page range, and it is stateless with no inputs. It does not discuss rate limits or error behavior in-line, deferring to the docs URL, so it falls short of a 5.

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?

Front-loaded with the substantive scope first, then labeled blocks (WORKFLOW, INPUT CONTRACT, DO NOT CONFUSE WITH) that are fast to scan. The trailing docs URL is mildly redundant given an output schema exists, but the whole description is dense and nearly waste-free.

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 zero-argument, read-only reference lookup with an output schema, everything an agent needs is present: content scope, stable-id behavior, downstream relationship, and sibling disambiguation. No gaps that would cause a wrong tool selection or misuse.

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 single response_format enum is fully documented in the schema, so the baseline is 3. The description's 'INPUT CONTRACT: No inputs beyond response_format' restates the schema rather than adding meaning such as when json is preferable.

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+resource ('what each house and planet signifies') and pins the exact source and scope (William Lilly's Christian Astrology 1647, twelve houses pp. 50-56, seven planets pp. 57-83). It distinguishes itself from the closest sibling by naming asterwise_get_vedic_significations as the Vedic-track alternative.

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?

Explicit workflow block states there is no BEFORE dependency (standalone) and identifies the downstream consumer, asterwise_get_western_daily_factors, whose factors cite these ids. A dedicated 'DO NOT CONFUSE WITH' line names the alternative tool, giving both when-to-use and when-not-to-use guidance.

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