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

The description goes well beyond the read-only/idempotent annotations by disclosing the computation engine (Swiss Ephemeris, Lahiri ayanamsa), no auth requirement, request rate limits (30/min/IP plus shared budget), and a specific edge-case behavior ('amanta month ... omitted entirely, never substituted'). It also notes that results are location-dependent based on actual sunrise/sunset.

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?

The description is dense but well-structured, proceeding from return values to usage guidance to technical caveats. Every sentence conveys necessary information, though it is longer than the two-sentence ideal. The front-loading of the main output and alternatives keeps it efficient, but slight trimming could improve readability.

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 tool with no output schema and multiple optional parameters, the description covers all essentials: what it returns, when to use it, how parameters interact, performance characteristics, and known limitations. It even addresses edge cases like missing amanta month. No critical gap remains for an agent to select and invoke the tool correctly.

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?

The input schema already provides 100% coverage with descriptive parameter comments, so the baseline is 3. The description adds value by explaining the relationship between parameters (e.g., 'Omit only if you pass latitude + longitude + timezone instead') and the behavioral impact of location on results ('window times derive from that location's actual sunrise and sunset'). This merits a 4.

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?

The description explicitly states the tool's function: 'Returns the Hindu panchang (daily Vedic almanac) for one date at one place' and enumerates the exact components (five angas, lunar month, sunrise/sunset, etc.). It also distinguishes from sibling tools by naming alternatives for full timing surfaces and birth-star nakshatra, making its scope unmistakable.

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?

Clear usage guidance is provided: 'Use this for "what is today's panchang / tithi / nakshatra" questions.' It explicitly tells when not to use it and what to call instead: 'If the user wants the FULL timing surface ... call get_muhurta_timings instead' and 'Nakshatra here is the DAY's nakshatra, not a person's birth star -- for that use get_birth_details.'

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