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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the agent knows this mutates state. The description adds the useful detail that the title is user-visible in the app, but never explains the destructive aspect (e.g. that it overwrites an existing title) or any auth/session requirements.

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 compact sentences, front-loaded with the action and scope; the second sentence adds display context. No wasted words, though the parenthetical example could be folded more tightly.

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 2-param tool with no output schema this is nearly adequate, but the unexplained destructiveHint and the undocumented session_token leave an agent guessing about overwrite behavior and session prerequisites.

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% for 2 params, so the description carries the burden. It meaningfully clarifies the 'title' parameter (project/task name, displayed as thread title) but says nothing about session_token or its format/source.

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 (name/set) and resource (this session's conversation thread) plus where it surfaces (the human's phone, app thread title). An agent can tell it apart from call/text/wait_for_reply, though it never explicitly contrasts with them.

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 parenthetical 'e.g. the project or task you are working on' implies what content to pass, giving soft usage context. There is no explicit when-to-use trigger, no when-not-to-use, and no alternative named.

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