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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered by structured data. The description adds genuine behavioral context beyond that by spelling out what fields come back, including attribution details (origin touch, ad title, Meta id) that annotations cannot convey.

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?

Front-loaded with the verb and the single-object scope, followed by a compact returned-field inventory and a short id-sourcing pointer. The field list is long but every item is meaningful payload information, with no filler sentences.

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 takes on the return-value burden and does so thoroughly, enumerating fields and nested attribution. Required params, error codes, and id provenance are covered between the description and the schema, leaving nothing an agent needs to call it 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?

Schema description coverage is 100% and both parameters carry their own 404/403 semantics in the schema, so the description need not document them. It contributes only the indirect hint that lead_id comes from list_leads, which is the baseline 3 when the schema does the heavy lifting.

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 ('Get one lead of an agent') and enumerates the payload it returns (name, phone, status, AI summary, custom fields, assignment, pin state, ids, attribution origin). It also distinguishes itself from list_leads, so an agent can separate the single-lead fetch from the bulk listing.

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 closing sentence 'Get the lead's id from list_leads' gives clear, actionable context for when and how to reach this tool, chaining it after the listing call. It offers no explicit when-not or exclusion cases, which keeps it short of a 5.

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