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

Annotations already declare readOnlyHint=true/destructiveHint=false, and the description adds real value beyond them: it discloses provenance discipline ('with source and date', 'never a URL found by search') and that no keys or values are returned. It does not cover output shape or pagination for the 'full' mode, so it falls just short of the top band.

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?

Dense but front-loaded: the core behavior leads, followed by a numbered route ranking and the detail note. Every clause carries information (ranking, provenance, read-only), though the parenthetical heavy style is slightly compacted.

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?

There is no output schema, so the description appropriately explains what comes back (ranked routes with source/date; procedure and evidence in full mode). Combined with 100% param coverage and read-only annotations, an agent has enough to invoke it correctly, though the exact response structure remains only lightly sketched.

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 the baseline is 3. The description mostly restates the schema semantics (slug from renkeimap_find_system or a pair suite id; detail='full' adds procedure and evidence) rather than adding new syntax or format guidance.

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+resource: it returns routes INTO one system, ordered by stability, and enumerates the three route tiers (official MCP server, API key/OAuth, file/screen). It explicitly names sibling renkeimap_pair as the route for the file/screen tier, so an agent can place it relative to siblings without opening another schema.

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 stability ordering (most stable first) and the 'never a URL found by search' rule give clear context for when this is the right call when trying to connect into a system. It stops short of explicit when-not-to-use or exclusion conditions versus other siblings, but the context is unambiguous.

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