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

Annotations cover the safety profile (readOnly, non-destructive), but the description adds substantial behavior beyond them: per-hop executable join_spec with real file/column names, null when a hop could not be tested, direction of stored verb/cardinality, measured row coverage semantics (blank key counts as a miss), PII flags, and the explicit boundary that it never returns data itself.

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?

Front-loaded with the core purpose, but the bulk of the content is a single sprawling sentence dense with em-dash clauses that is hard to parse on first read. Every clause earns its place informationally, yet the structure could be broken up for readability.

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 full burden of explaining the return shape and does so thoroughly: join_spec per hop, verb/cardinality/direction, strength, coverage, caveat, owning systems, and PII fields. Nothing an agent needs to interpret the result is missing.

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 baseline is 3, but the description adds meaning the schema lacks: names are accepted in any case while the answer uses the map's own spelling. It also clarifies the parameters are object names (start/target), reinforcing the schema examples.

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 (navigation/join-path resolution) and resource (objects on the map), and the 'map as GPS' framing plus 'shortest verified join path' clearly separates it from siblings like fetch, search, and get_object. An agent can tell what it returns without opening the 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?

'Use it before fetching data in your human's own systems: the route tells you where to look, by which columns, and how much to trust each step' gives clear when-to-use context and implicitly contrasts with fetch. It stops short of naming explicit exclusions or conditions where routing is pointless (e.g., single known table), so not a full 5.

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