Find stops

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

With readOnlyHint and openWorldHint already present, the description still adds real behavior: multiple matches are returned rather than one guessed, distances are true straight-line metres, and coverage is limited to Attica (OASA buses, trolleys, metro, tram). Error handling and rate limits are not covered, but the multi-match and distance semantics are the traits an agent most needs.

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?

Four sentences, each front-loaded with the operative fact: what it does, name-matching tolerance, preferred input mode, ambiguity/coverage caveat. No sentence is filler and the most decision-relevant guidance (use lat/lon) comes early.

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 must carry return behavior, and it does explain that candidate sets (not a single guess) come back with straight-line distances. The geographic boundary is stated. It stops short of describing the fields in each returned stop record, which an agent composing a follow-up call would find useful.

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 86%, so the baseline is 3, but the description meaningfully extends it: the query parameter tolerates Greek or Latin script, ignores accents and case, and accepts common English spellings like 'Piraeus'. It also reinforces that lat/lon is a paired, faster path. It adds nothing for line, limit, or radius_m beyond the schema.

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?

The first sentence gives a specific verb (find) and resource (OASA stops) plus the two supported lookup modes (name, coordinate). The resource is clearly distinct from every sibling, which deal with arrivals, routes, lines and vehicles rather than stop lookup. Scope is further pinned down with the operator/geography sentence.

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?

It states which lookup mode to prefer ('Passing lat and lon is the fastest and most reliable route') and explains why ambiguity is handled by returning candidates instead of guessing. It also gives an explicit geographic exclusion ('Covers Attica (greater Athens) only'). It does not, however, name sibling tools for follow-up needs such as arrivals at a found stop.

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