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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds value beyond that by describing the return shape — each number, where it was found, and a 'callable' flag indicating whether OsmO can place the call — which hints at the downstream place_call path. It doesn't discuss result limits or what happens when no numbers are found, so it isn't fully transparent.

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 core sentence is front-loaded and efficient, but the tail is fragmented: 'Read-only.' is only two words, and the final 'For example a bank, airline...' duplicates the earlier 'e.g.' example and reads as an afterthought. The exclusion sentence is correct in substance but sits awkwardly between the return-value description and the annotation restatement.

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 one-parameter, no-output-schema tool, the definition covers what the tool searches, what it returns, and what it excludes — enough to call it correctly. Minor omissions remain, such as behavior when no numbers exist or how many results come back, but nothing critical for invocation.

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?

There is a single parameter with 100% schema description coverage ('The company, e.g. "HDFC Bank" or "Delta Air Lines"'), so baseline 3 applies. The description's 'HDFC customer care' example reframes the input as a query phrase but adds no new constraints or formatting rules 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?

States a specific verb ('Finds') and resource ('customer care or helpline numbers'), plus scope limited to the user's own country. The exclusion 'Does not cover local shops or people' separates it from the business/contact lookup siblings without needing to name them. An agent can decide in one read whether this is the right tool.

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?

Gives clear context for when to use it — helpline numbers for a company the user has a relationship with, with concrete categories (bank, airline, mobile carrier, insurer, delivery company) and an explicit exclusion. It stops short of naming an alternative tool for the excluded cases, so routing to a sibling is left implicit.

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