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

Annotations already declare safe read-only idempotency, and the description adds substantial semantics beyond them: the exact tri-state vocabulary and what each state means, the warning that 'not_indexed_coverage_unknown' is explicitly NOT evidence of missing commentary, the category 3/4 scoping and the in_tafsir_categories:false marker for out-of-category hits. It also discloses the return shape (totals per status plus a curated-index caveat note).

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 purpose, then the tri-state definitions, then parameters, navigation escape hatch, and examples. The tri-state enumeration is dense but each clause carries load; the bilingual Arabic title line is mildly redundant with the English title.

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?

No output schema exists, yet the description covers the return contents (per-book tri-state with page_id and printed page, totals per status, index-limitation note) and the idempotent read semantics. An agent has everything needed to call it and interpret the result 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?

Schema coverage is 100%, so the baseline is 3, but the description adds the mutual-exclusivity/alternative semantics (aya_id OR surah+aya) that the all-optional, zero-required schema does not itself express, plus concrete value examples. The response_format capability requirement is already fully documented in the schema.

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 and resource — a per-aya tafsir coverage report that cross-references the user's downloaded tafsir shelves (categories 3 and 4) against the curated tafseer.db index. It also draws its boundary against siblings by declaring 'Never text-searches', distinguishing it from shamela_get_tafseer_of_aya and shamela_get_tafseer_texts.

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?

Gives explicit calling modes ('Pass either aya_id (1..6236) OR surah+aya'), two concrete examples, and routes the agent to shamela_get_toc for books in unknown-status. It does not, however, explicitly say when to prefer this over the tafseer-text siblings, leaving that to inference from 'Never text-searches'.

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