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

Annotations already declare the full safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description only needs to add context, and it does contribute one genuinely useful behavioral detail: unsubscribed contacts are still returned and are marked rather than filtered out. Beyond that it says nothing about result ordering, pagination, or size limits, which matters for a list tool that may return many records.

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?

A single front-loaded sentence with the resource scope first and the returned-field detail in a compact parenthetical. Every clause carries information and there is no filler or repetition of the title.

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?

With no output schema, the description must convey what comes back, and it does list the principal fields (name, firm, email, title, LinkedIn, notes) plus the unsubscribed-marker behavior. The omission is operational detail — pagination, ordering, and result caps — which an agent calling a contacts list would want but which is a modest gap given the tool's low complexity.

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 parameter and the schema documents it fully ("Optional text in name, firm or email", 100% coverage), so the schema already carries the semantic load. The description makes no reference to the search filter at all, adding no meaning about matching behavior (substring vs. exact, case sensitivity) beyond what the schema states.

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 opens with a specific verb+resource pair ("Lists the user's private investor contacts") and enumerates the returned attributes, so it is unambiguous what the tool does. The word "private" implicitly separates it from a public investor search, but no sibling (e.g., find_investors, add_investor_contact) is named to make the distinction explicit.

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?

Usage is only implied: "the user's private investor contacts" signals this reads the caller's own stored contacts rather than searching a directory, which is the natural contrast with find_investors. There is no explicit when-to-use statement, no mention of when not to use it, and no pointer to the alternative tool for searching investors outside the user's list.

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