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

Annotations cover the safety profile (readOnly=false, destructive=false, openWorld=false), and the description adds real behavioral context beyond them: authentication is required, the tool stamps provenance source="agent" server-side, and it explicitly sends no email. It stops short of saying what happens on duplicate emails or with an empty payload, which matters given idempotentHint=false.

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?

Four short sentences, front-loaded with the core action and return value, then side-effect boundaries. Nothing is wasted, though 'Requires authentication' is a fairly generic tail statement.

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 correctly compensates by stating the return value (new lead id). For a mutation tool it covers auth, side effects, and provenance; the remaining gap is behavior on duplicates and on an all-optional empty payload.

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 description coverage is 100%, so every one of the 7 optional fields is already documented in the schema (including that omitted email means held research). The description adds no per-parameter meaning of its own, so the baseline 3 applies.

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 and resource ('Add a single lead to the authenticated user's outreach book') and scopes it to one lead, which implicitly separates it from bulk or search operations like search_outreach_leads. It never names a sibling explicitly, so the differentiation is inferential rather than stated.

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: an agent infers it should call this when it wants to create a lead. The clause 'Does not send any email' does helpfully signal this is not the outreach-sending path, but there is no explicit when-to-use vs. when-not guidance or pointer to update_outreach_lead_status / search_outreach_leads.

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