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

No annotations are supplied, so the description carries the full burden. It does disclose the shape of what comes back (scores, per-pillar breakdown, location, donation link), which implies a read-only aggregation, but it says nothing about error behavior for invalid or duplicate slugs, ordering of results, or whether the comparison is cached/computed.

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 front-loaded sentence that states the operation, its cardinality constraint, and the output facets with zero filler. It could be marginally improved by separating scope from output, but nothing is wasted.

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 and no annotations, the description must explain both behavior and returns. It lists the four output components but gives no structure, ordering, or error details, leaving meaningful gaps for a tool whose entire value is the comparison payload.

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 0%, but there is only one parameter and the description explains that it is a slug-based identification of NGOs and that the count must be 2 to 3. That adds the semantic meaning of 'slug' beyond the schema's type/minItems/maxItems constraints, though it does not clarify slug format or duplicate handling.

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 verb and resource ('Compare 2 à 3 associations') and enumerates what the comparison covers (global score, pillar breakdown, location, donation link). It is clearly distinct from single-record siblings like get_ngo, though it never names an alternative explicitly.

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 use case (side-by-side comparison of a small set of NGOs) is implied by 'Compare 2 à 3 associations', but there is no explicit guidance on when to prefer this over get_ngo (single lookup) or top_ngos (ranking), nor any prerequisites for obtaining slugs.

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