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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: deleted objects return a tombstone with status "gone" rather than erroring, which is non-obvious and prevents the agent from misreading a lookup. It stops short of describing pagination or partial-result behavior, but with a read-only single-record tool that is a minor gap.

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 is front-loaded in the first clause, the identifier enumeration follows as supporting detail, and the usage boundaries close it out. Every sentence carries distinct information with no restatement of the name or schema.

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 read tool with full schema coverage, annotations, and an output schema, the description covers purpose, accepted inputs, an edge case (tombstones), and sibling routing. Nothing an agent needs to call it correctly 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% and the id parameter is already documented, so the baseline would be 3. The description earns above baseline by enumerating the accepted identifier families (sat-ids, section slugs, legacy OSM ids, Wikidata QIDs, GTFS stop ids, AED-registry ids), which is meaningfully richer than the schema's two examples and tells the agent it can pass IDs from other systems.

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 (fetch) plus resource (full JSON-LD record for one object by identifier) and immediately delineates scope versus siblings. An agent can tell this apart from search, day_trip, and plan_route without opening any 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?

Explicitly says when to use it (you already have an identifier, from search or an earlier response) and when not to (not for searching by name, not for trip planning), naming the alternative tool for each exclusion.

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