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 clear. The description adds exact-match semantics and the endpoint shape, but it does not explain what happens on no match, how many results are returned, or any pagination behavior.

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?

It is three compact sentences with the exact-match behavior and the key use case front-loaded. The endpoint reference is secondary and does not bury the decision-relevant information.

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 should ideally clarify what a successful find returns, such as matching lead objects or an empty result. It covers the input behavior and safety context adequately but leaves a meaningful gap around return values and no-match behavior.

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 the schema already documents fields, list_id, and match_all in detail. The description reinforces that fields are exact-match keys and restates the match_all rule, but adds little beyond the schema's own parameter descriptions.

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 description states a specific operation: exact-match lookup on one or more fields of a list, with examples such as phone number or email. It distinguishes itself reasonably from broader retrieval tools like myphoner_list_leads or myphoner_search_leads by specifying 'exact match,' though it does not name those siblings directly.

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 gives a concrete usage scenario, checking whether a lead already exists, but does not say when to prefer this over myphoner_search_leads or myphoner_list_leads. The guidance is implied rather than explicit about alternatives or exclusions.

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