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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, non-open-world, so the safety profile is covered by structured data. The description adds that output is one block per account with its logo, which is modest but real UI/behavior context. It does not cover pagination, channel coverage when none are connected, or output shape beyond the visual metaphor.

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?

Two tightly packed clauses with no filler and the scoping constraint (by connected channel, over a period) is front-loaded. Slightly denser than ideal but every phrase 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 single-optional-parameter read tool with no output schema and annotations covering safety, the description is close to sufficient. It is thin on what happens with zero connected channels and does not describe the aggregate set returned, which matters since there is no output schema to fall back on.

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?

Only one parameter exists and the schema description coverage is 100%, so the schema already documents period_days with its default, min and max. The description adds 'sur une période' but no syntax, boundary behavior, or timezone details. Baseline 3 is correct when the schema does the heavy lifting.

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 ('AFFICHE UN ÉCRAN') and resource (stats by connected channel), and explicitly anchors to the sibling ficiel_get_stats by saying the aggregates are 'les mêmes... découpés par canal connecté'. That differentiates it from get_stats and from channel-adjacent tools like get_channel_status, though 'un écran' is UI-flavored rather than API-precise.

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 reference to ficiel_get_stats implies when to choose this tool (same aggregates but split by channel), but there is no explicit when/when-not statement or guidance on choosing between this and ficiel_get_channel_status or ficiel_compare_periods. Usage is implied rather than stated.

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