system_open_url

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

Annotations already declare the side-effect profile (readOnlyHint=false, openWorldHint=true, idempotentHint=true, destructiveHint=false). The description adds the useful constraint that only http/https schemes are accepted and that no permissions are required, but says nothing about the human-approval flow implied by the _approvalId parameter or about browser foregrounding/tab behavior.

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?

Two short sentences, front-loaded with the action and immediately followed by the scheme constraint. The bracketed '[v1.0.0; permissions: none]' metadata adds little operational value but is brief and does not obscure the core instruction.

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 a full-coverage schema, an output schema, and annotations covering safety and open-world scope, the description supplies the one thing not fully carried elsewhere: the scheme restriction. It is nearly complete; only the approval/idempotency workflow for this write-like action is left implicit.

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 description coverage is 100%, so all three parameters (url, _approvalId, _idempotencyKey) are documented in the schema. The description only restates the accepted URL scheme, adding no format, length, or idempotency semantics beyond structured data; 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?

States a specific verb and resource (open a URL in the default browser) and constrains input scope to http/https, which is more precise than the bare name. It does not, however, distinguish itself from close siblings like safari_open_tab or system_open_app, leaving the agent to infer which opener applies.

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 is implied rather than stated: an agent can infer this is for handing an http(s) link to the OS default browser, and the scheme restriction excludes other cases. There is no explicit when-to-use guidance or named alternative for cases like 'open a file' (finder_open_file) or 'open a specific app' (system_open_app).

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