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

The description discloses the single most important and non-obvious behavior: the tool 'opens nothing by itself' and only returns a guide, which directly explains the readOnlyHint and closed-world annotations rather than restating them. It also explains the upstream constraint (Thumbtack's Partner Platform API is gated and request-only), which justifies why a browser-automation handoff exists.

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 key point — that this returns instructions and performs no action — is front-loaded in the first sentence, followed by the execution path. The final sentence on the official API is relevant justification but slightly verbose, including a low-value '(checked 11 Oct 2026)' provenance note.

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 parameters, no output schema, and full annotation coverage, the description supplies what is missing: what it returns (screens, buttons, fields) and what the agent should do next. It does not clarify how the returned procedure relates to the live browser session (e.g., whether it is static or account-specific), a minor remaining gap.

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 tool takes zero parameters, so there is no parameter meaning to add and the baseline of 4 applies. Nothing in the description conflicts with the empty schema.

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 names a specific verb and resource ('List leads in the user's own Thumbtack account') and immediately clarifies the tool's real output: step-by-step instructions rather than the data itself. It does not differentiate itself by name from siblings such as thumbtack_export_past_leads or thumbtack_list_reviews, so it stops short of a 5.

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 clear usage context — call this to get the procedure, then execute it with the cotlet_browser_* tools in the user's Thumbtack Cloud Browser. There are no explicit exclusions or named alternatives for cases like exporting historical leads, which keeps it below 5.

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