Get ad posts

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

Annotations already mark it read-only; the description adds genuinely useful behavior: it returns posts with card_uri/media, accepts about 200 ids, and defaults tweet_type to PUBLISHED including promoted-only tweets. This goes beyond the schema's enum and gives the agent a realistic expectation of request bounds. No contradiction with readOnlyHint.

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?

Three short sentences front-load the core purpose before the alternative guidance and constraints. There is no filler and no repetition of schema fields.

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?

For a simple read-only fetch with three parameters and no output schema, the description conveys purpose, source, return emphasis, batch limit, and default parameter behavior. The only omitted detail is exact behavior when more than ~200 ids are passed, which is minor.

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 coverage is low (33%), but the description fills gaps: tweet_ids are sourced from x_ads_list_ads and limited to ~200; tweet_type gets a default of PUBLISHED. account_id is already documented in the schema. It does not elaborate on the SCHEDULED or DRAFT enum values, but the schema already lists them.

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 uses a specific verb ('Fetch posts behind ads'), identifies the exact input source ('tweet_id from x_ads_list_ads'), and distinguishes itself by emphasizing that it returns card_uri and media. This clearly separates it from generic post fetching and related card/media siblings.

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 explicitly says when to use this tool: 'Use this, not a generic post fetch, to tell whether an ad has a card/image.' It also provides an input prerequisite and default behavior. However, the alternative is described generically rather than naming a specific sibling, so it stops short of full routing.

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