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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds two genuinely behavioral facts — the result window ('this week') and sort order ('earliest first') — but leaves the week boundary undefined and says nothing about behavior when a city is unknown or has no Jumu'ah listings.

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?

A single sentence that front-loads the resource and appends scope and ordering with no filler. Every clause carries information.

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 one-parameter read tool with rich annotations and no output schema, the description tells the agent what it returns, for which city, over what window, and in what order. Minor remaining gap: whether results span multiple masjids or include khutbah start times, which matters given the khutbahs sibling.

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 100% and the schema description already explains the 'Anaheim, CA' vs '/anaheim-ca' formats. The description's phrase 'in a city' adds nothing beyond the parameter itself, so the baseline of 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?

The description names a specific resource (Friday/Jumu'ah prayer times) plus scope (masjids in a city) and result ordering (earliest first). It distinguishes itself from prayer_times and iqamah_times only by implication through the word 'Jumu'ah'/'Friday' — it never names those siblings, so an agent has to infer the split.

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?

The word 'Friday' implies the usage occasion, but there is no explicit statement of when to pick this over prayer_times, iqamah_times or khutbahs, and no exclusions or prerequisites. Usage is inferable rather than stated.

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