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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, and the description is consistent ('Returns'). It adds useful behavioral context beyond that: the result is a two-part payload (candidate contacts plus a message template) and it is only the first half of a workflow whose second step is create_referral_invites.

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 three sentences are reasonably front-loaded, but 'for recommending LMCP to a colleague' and 'when they want to invite or recommend someone' say substantially the same thing, and the return contents are restated before the chaining note. One redundant clause could be cut.

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?

The tool is simple (one optional parameter, read-only, output schema present), and the description covers what it returns and how it sequences with create_referral_invites. With an output schema present, return-value detail is rightly left out; the only gap is why some contacts are excluded as non-emailable.

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 optional limit parameter and schema description coverage is 100%, with the schema already documenting the default of 60 and minimum of 1. The description adds nothing about this parameter, so this sits at the baseline for fully documented schemas.

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 gives a concrete verb and resource: returns the user's emailable contacts plus an invite template. The qualifier 'emailable' and the template differentiate it from the nearby list_contacts tool, though the distinction is implicit rather than stated as a contrast.

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 the triggering situation ('when they want to invite or recommend someone') and names the follow-on step, create_referral_invites, which generates each chosen person's unique link. It stops short of explicitly excluding alternatives like list_contacts, but the workflow context is clear.

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