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

With no annotations, the description carries the full behavioral burden and does well: it discloses cost (free), an authentication prerequisite (signed in as the account that ran the study), and the key behavioral limitation that MCP returns text, so this yields a link rather than a file. It does not describe what happens for an invalid or unknown sim_id, which is the main remaining gap.

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 lead sentence front-loads the tool's job and the return payload, and the mode-by-mode PDF table is useful, non-redundant information. It is slightly repetitive: the 'choose PDF / gives the link, not the file' idea is stated twice.

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?

There is no output schema and no annotations, so the description must supply the return shape and the behavioral contract itself. It lists the returned fields (sim_id, status, mode, results_url, pdf_available, pdf_note) and explains per-mode PDF behavior, auth, and cost, leaving nothing an agent needs in order 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?

There is a single parameter, and the schema documents it at 100% coverage ('The id of a study you ran'), matching the description's own phrasing. The description adds nothing beyond the schema, 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?

The description states a concrete verb-and-resource pair: it returns a study's page URL and PDF availability, and it explicitly says it returns a link, not the file. That is specific enough to act on. It never distinguishes itself from the sibling get_simulation, so an agent cannot tell from this text alone which one to call to inspect a study.

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 context is clear: it is free, it applies to a study you ran, and you must be signed in as the account that ran the study. It also states which study types (Pulse, compare_options, screen_creatives) produce a PDF, and which (Ads Labo, pricing, MaxDiff) do not. It names no alternative tool and gives no exclusion rule, so it falls 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.