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

With no annotations, the description carries the full burden and does disclose two real operational traits: a 1-credit cost and the exact auth header format (Authorization: Bearer sk_instapi_...). It omits return shape, result limits, and pagination, but the auth and billing disclosures are substantive.

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, front-loaded sentences: capability first, then cost, then auth requirement. No filler or restatement of the tool name.

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 single-parameter search with no output schema and no annotations, the description covers the essentials an agent needs to invoke it (what it searches, cost, auth). It is slightly incomplete in not hinting at the result structure, but nothing blocks correct invocation.

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?

Only one parameter exists and schema coverage is 100%, so the schema already documents the query parameter and its example. The description adds nothing beyond what the schema states, matching the baseline-3 rule for high coverage.

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 (Search) and the exact resource scope (Instagram users, hashtags, and places) keyed by keyword. This clearly separates it from the user-scoped siblings instagram_user_posts and instagram_user_profile.

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 description implies usage via the 'by keyword' framing and discloses a cost, but never states when to prefer this tool over the sibling user/profile tools or what happens when a query matches multiple entity types. Guidance is inferable rather than explicit.

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