update_account

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

With no annotations, the description carries the full behavioral burden. It earns credit for disclosing partial-update semantics ('only provide the settings you want to change') and explaining setting behaviors. But as a mutation tool it omits side effects (e.g., conflict between username and delete_username set together), propagation to linked devices, permission requirements, and success/return 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?

Four sentences, properly front-loaded: purpose first, then usage guidance, then param semantics, then sibling routing. The param explanations partially duplicate schema descriptions, which costs a point, 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 write tool with zero annotations, no output schema, and ~77 siblings, the description covers the primary routing and partial-update behavior but leaves gaps: no return-value/confirmation info, no error/conflict behavior, and no mention of two of six parameters.

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 baseline 3 applies. The description adds minor framing (the '@username alias' format, delete_username semantics, grouping as privacy/identity settings) but largely restates schema text and omits two params entirely: device_name and unrestricted_unidentified_sender, the latter being the most jargon-heavy.

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+resource: 'Update Signal account-level privacy and identity settings.' The concrete param explanations (discoverable_by_number, number_sharing, username, delete_username) make the scope tangible and distinguish it from siblings like update_configuration, update_profile, and update_contact, reinforced by the explicit routing sentence.

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?

Provides explicit guidance: 'All parameters are optional — only provide the settings you want to change' tells the agent this is a partial-update tool, and 'Use update_configuration for messaging settings (read receipts, typing indicators)' names the alternative and the condition. However, it never disambiguates device_name from the sibling update_device, and doesn't route to update_profile/set_pin for adjacent account surfaces.

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