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

Annotations already cover the read-only/idempotent/non-destructive profile, and the description adds real value on top: the limit scoping to organic results only, the guaranteed marking of sponsored placements, and concrete anonymous rate limits (60/hour, 300/day per IP and session). The 'no API key or signup' note also clarifies auth. Only the return shape is left unspecified.

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?

Purpose and the limit caveat are front-loaded well, but 'TerraMCP is a Wrench AI service' is service branding that does not help an agent select or invoke the tool and dilutes an otherwise tight definition. Rate-limit and auth notes do earn their place.

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 two-parameter read-only tool with annotations carrying the safety profile and no output schema, the description supplies the operational context an agent needs: rate limits, no-signup access, and the organic/sponsored distinction. Nothing critical is missing, though return format and pagination are not addressed.

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%, so both parameters are fully documented in the schema (limit default/max and category slug). The description's 'limit applies only to organic results' largely restates the schema's 'maximum organic sources to return,' adding only marginal clarity. Baseline 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?

Specific verb and resource: 'Return highest evidence-quality organic sources and separate sponsored placements.' The scope ('browse a category') and the organic/sponsored split make it distinguishable from search_sources, though it never explicitly names that sibling. Clear but not fully differentiated.

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?

'to browse a category' implies the use case (category-based discovery rather than keyword search), but there is no explicit when-to-use vs search_sources or list_categories, and no exclusions. Usage is left to inference.

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