open_sessions

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

Annotations only declare readOnlyHint=false and openWorldHint=true, so the description adds real value: it discloses that one session_id is returned per account and that sessions are concurrent and must be closed. It does not note limits on how many can be opened or what happens on partial failure.

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 purpose sentence, followed by a compact per-parameter list and a lifecycle note. Slightly ragged line-broken formatting, but no sentence is wasted.

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 3-param, all-optional tool with an output schema, the description covers purpose, each parameter, the return shape and cleanup. Only the site/profiles interaction and any concurrency cap are missing.

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 0%, so the description carries the burden and does explain all three params: 'site' opens every saved login for a site, 'profiles' takes names or account emails, 'url' is the optional page. It leaves the relationship between site and profiles (alternative vs. combined) unstated.

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 ('Open several logins at once, each in its own browser') and its bulk scope distinguishes it from the singular open_session sibling without ambiguity.

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?

Gives concrete usage context ('you can work on them in parallel') and a lifecycle rule ('close each one when done'). It does not explicitly contrast with open_session for the single-account case, but the 'several at once' framing implies the split.

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