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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful non-schema context — the endpoint and the 20-credit Tier 2 cost — but says nothing about auth requirements, rate limits, or how the 5-level cascade is returned.

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 tight fragments with the domain-defining qualifier ('finest grain') front-loaded, followed by machine-readable group/endpoint/cost metadata. Every element earns its place, though the telegraphic style sacrifices some explanatory value for brevity.

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 and the input schema is fully documented, so return values and parameters need not be restated. The description supplies the one thing structured data cannot — the domain placement of 'prana' within the Chara level hierarchy and its minute-scale resolution — but omits selection guidance against the four sibling levels, which is the main remaining gap.

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%, so the body fields (date, time, latitude, longitude, timezone handling, fields, precision) are already fully documented in the schema, and the description adds no parameter meaning beyond that. Baseline 3 is appropriate when the schema carries the entire parameter burden.

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 names the specific system and level ('Chara Pranadasha') and, critically, places it as the 'finest grain' of a '5-level cascade', which is exactly the distinction an agent needs against siblings like chara_maha, chara_antar, chara_pratyantar and chara_sookshma. It stops short of stating the compute/return verb explicitly, but the resource and its position in the family are unambiguous.

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 explicit when-to-use or when-not-to-use guidance and no routing to alternatives such as chara_sookshma when a coarser grain suffices. 'Finest grain' and 'minute-scale duration' imply the deepest-resolution use case, but the agent must infer that selecting this tool versus the four shallower Chara levels depends on desired time resolution.

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