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

Annotations already declare readOnly/idempotent/destructive hints. Description adds crucial behavioral details: 'Returns base64-encoded PDF content' (output format), 'Free' (cost), and completion requirement. No contradiction with annotations.

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?

Five efficient sentences front-loaded with action, then return format, prerequisites, and parameter source. Zero waste—every sentence provides unique value not duplicated in structured fields.

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-parameter download tool with good annotations, description adequately covers return format (base64 PDF), cost, prerequisites, and parameter sourcing without needing output schema documentation.

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 has 100% coverage (baseline 3), but description adds meaningful provenance context: 'report_id from atlas_start_report response or atlas_list_reports', helping the agent understand parameter sourcing beyond the schema definition.

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 specific action 'Download' with resource 'completed report as PDF', clearly distinguishing from sibling 'atlas_get_report' (which checks status) and 'ceevee_download_report' (different namespace).

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?

Explicitly states prerequisite: 'Confirm report status=completed via atlas_get_report(report_id) first'. Also identifies parameter source from 'atlas_start_report response or atlas_list_reports', providing clear workflow guidance.

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