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

Annotations give readOnlyHint=true and openWorldHint=false, and the description goes well beyond that: it discloses the free-tier limitation per country, the meta.free_years escape hatch, and the specific error codes (country_not_available, key_required). It also describes the return payload per country (issue counts, last issue number, French/Arabic edition coverage, summary counts).

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?

Purpose and the 'use it first' directive are front-loaded, and the per-country paragraphs carry real information about differing coverage dates and return fields. However, the Morocco and Tunisia passages repeat country semantics that the schema's country parameter already states, making it longer than strictly needed.

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 no output schema, the description compensates by enumerating the returned fields per year (issue count, last issue number, bilingual edition counts, summary coverage). Combined with the auth/error behavior, an agent has everything needed to call this 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 description coverage is 100% and both parameters are already fully documented with enums, defaults and country semantics. The description's 'Takes only the optional lang and country' restates the schema rather than adding new meaning, so the baseline 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?

States a specific verb+resource ('List the years covered by the index of the Journal Officiel') and immediately scopes it to three named gazettes. It is clearly distinguishable from siblings like list_jo_issues and search_jo_titles, which operate at issue/title granularity rather than year granularity.

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?

Explicit sequencing: 'Use it first, to see which years exist before listing the issues of a year' names both the when and the downstream tool. It also documents the precondition that without an API key only Algeria answers and that TN/MA return key_required, which is actionable routing guidance.

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