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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds behavioral context beyond annotations by revealing the output format (CSV) and that it is for download, plus the expectation that input comes from a prior search/query. This is useful but does not dive into edge cases.

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?

The description is two sentences, front-loaded with the primary purpose, and every sentence adds value. No redundant or wordy content.

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 (2 params, no output schema). The description covers what it does, the input source, and the output format. Annotations cover safety. There are no obvious missing details that an agent would need to invoke this tool 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% (both contacts and filename are described in the schema). The description adds extra semantic value by clarifying the 'contacts' parameter should come from 'a previous search or Xmagnet query,' which helps the agent understand the expected provenance of that array.

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 action ('Export a list of contacts to CSV format for download'), naming both the verb and the resource. It clearly distinguishes itself from sibling tools like search_contacts or save_contacts_to_crm by focusing on export/download.

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?

It specifies the context: 'Pass the contacts array from a previous search or Xmagnet query,' indicating this tool is used after a search/query to export results. It does not explicitly name alternatives or exclusions, but the guidance is clear enough for an agent to choose this tool when exporting contacts.

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