get_contacts

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

With no annotations, the description must disclose behavioral traits. It reveals that the tool depends on the mailbox index and returns ranked results. However, it does not explain behavior when the index is empty (e.g., empty list vs. error) or describe side effects (like index locking). More detail on the 'analytics sample window' would improve transparency.

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 description is two sentences totaling 37 words. The first sentence immediately states the core function and output; the second adds usage context and a prerequisite. No filler or redundancy. Every sentence serves a purpose.

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?

Given the tool's simplicity (1 parameter, no output schema, no annotations), the description covers the essential: output (ranked emails), ranking basis (interaction volume), and a key prerequisite (index populated). It lacks explanation of the 'analytics sample window' and error cases, but overall it is sufficiently complete for an agent to use the tool correctly.

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?

The sole parameter 'limit' is fully described in the input schema (Max contacts to return, default 100). The description does not add any extra meaning or usage hints beyond what the schema provides. With 100% schema coverage, a score of 3 is appropriate.

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 uses a specific verb ('Return') and resource ('most frequently contacted email addresses ranked by interaction volume'), clearly stating its function. It distinguishes itself from sibling tools by focusing on frequency-based ranking, which is unique among the listed tools.

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?

The description provides explicit usage guidance: 'Use to identify key correspondents or to pre-populate recipient lists.' It also includes a prerequisite ('Requires the local mailbox index to be populated — call sync_emails first'), which helps the agent decide when to use this tool. However, it does not mention when not to use it or compare with alternatives like get_follow_up_candidates.

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