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

Annotations already declare the tool read-safe and idempotent. The description adds meaningful behavioral context: results are limited to employers with active listings, the market is Portugal, and it reveals the specific metrics returned. This goes beyond what annotations provide without contradicting them.

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?

Three compact sentences: the first states purpose and scope, the second previews return fields, and the third gives usage guidance. Every sentence earns its place, and the core action is front-loaded.

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?

The tool is simple (no required params, no nested objects, 100% schema coverage, and an output schema exists). The description covers purpose, scope, return contents, and a concrete follow-up use case, leaving no material gap for an agent to call it 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%, so all three parameters (name, limit, sector) are already documented. The description adds no parameter-specific semantics beyond reinforcing that the search targets employers, which is the baseline expectation. A 3 is appropriate.

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 states a specific verb and resource ('Search employers') with a clear geographic scope ('with active listings in Portugal'), and enumerates the returned data fields. It is readily distinguishable from sibling tools like search_jobs and search_articles.

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 description explicitly tells the agent when to use this tool ('when the user wants to explore who is hiring') and even suggests using it to restrict a subsequent search_jobs call. It does not explicitly list exclusions or alternative conditions, but the guidance is clear enough.

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