Prayer times

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

Well beyond the readOnly/idempotent annotations, it discloses the underlying astronomy library (adhan.js) matching the website, coordinate rounding to 4 decimals, the default-method resolution order, the >48° high-latitude recommendation with override, and the output encoding (local HH:MM 24h plus UTC ISO). It also defaults defaults explicitly (today, current time), which the agent cannot infer from structured fields.

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 core verb+resource+scope before the detail, and most sentences carry real information. However, enumerating all 13 calculation methods duplicates the schema enum verbatim and the trailing website URL is low value for an agent, so a small trim is possible.

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?

With 11 all-optional parameters and no output schema, the description does the right work: it explains the defaulting chain for method/asr/date/now and sketches the return payload (per-day times in local and UTC, Hijri date, next prayer countdown). It doesn't describe the top-level response shape (e.g., array of days vs. single object), which is the remaining gap for a no-output-schema tool.

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 already 100%, so the baseline is 3, but the description adds genuine meaning: the 48° threshold that motivates highLatitudeRule (not in the schema), the interaction that city sets coordinates/zone/method, and that the site-equivalent rounding is applied. Minor overlap with the schema's enum list keeps it from a 5.

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 (Islamic prayer times) with the exact prayers returned, both input modes (coordinates+IANA zone or known city), and the temporal scopes supported (one day, several days, whole month). The scope is instantly distinguishable from siblings like calc_hijri or time_world_clock.

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?

Usage context is clear from the capability statement — you call this when you need prayer times for a place/time range, and the description explains the two input patterns (city shortcut vs. coordinates+timezone). It stops short of naming alternatives or stating exclusions (e.g., when to use calc_hijri alone for Hijri conversion), which keeps it below a 5.

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