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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), yet the description adds genuinely new behavior: unknown values resolve to null, placeholders flag coming-soon sources, no API key or signup is needed for discovery, and anonymous rate limits are 60/hour and 300/day per IP and session. That rate-limit and null-handling detail is exactly the context annotations cannot convey.

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 purpose is front-loaded, but the description is a run-on mix of purpose, input syntax, null behavior, branding ('TerraMCP is a Wrench AI service'), and rate limits, with several terse fragments ('Unknown values are null. Placeholders explicitly show coming-soon status.'). It is information-dense but scattershot, and the branding sentence is borderline filler.

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, the description carries the return-value burden and does describe the payload (evidence, access requirements, router_tools) plus null/placeholder behavior. Combined with the disclosed auth-free discovery and rate limits, an agent has enough to invoke it correctly; only pagination/response shape is left implicit.

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 the baseline is 3, but the description adds value beyond the schema: it documents that -api/-mcp/-server suffixes are optional and that unknown values are returned as null. This clarifies accepted input forms and failure behavior that the schema alone does not state.

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 a specific verb and resource ('Get full source evidence, access requirements and router_tools') and names the return payload. It also positions itself relative to the sibling search_sources, so an agent can distinguish the two. The only weakness is that 'source evidence' is somewhat abstract without domain knowledge.

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 frames the tool as 'the recommended starting point after search_sources' and tells the agent to feed it 'a returned slug', giving clear sequencing context. It stops short of stating when NOT to use it or naming alternatives beyond search_sources, so it is strong context rather than full when/when-not guidance.

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