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

Beyond the annotations, the description discloses that this records a receipt without subscribing, that the reply count echoes input rather than verifying a receipt, and that shared seen state may already be ahead. It also adds the sign-in or linked-agent requirement and warns not to derive the cursor from filtered reads.

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?

The purpose is front-loaded, followed by targeted warnings, state semantics, and the authentication requirement. Every sentence carries operational information and there is no padding.

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 mutating, open-world tool with annotations and an output schema, the description covers the main behavioral risks, usage caveat, state semantics, and auth requirement. It leaves some destructive-impact details implicit, but the critical selection and invocation guidance is present.

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 50%, with space_id and channel_id documented in the schema, while thread_id and observed_reply_count lack schema descriptions. The description adds useful semantics for the reply count but names it 'requested_observed_reply_count', which does not match the actual parameter name, and it does not clarify thread_id.

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?

The description states a specific action: recording the opening and last reply sequence this task received in a thread. It also distinguishes the tool from space_read_thread by warning that filtered reads skip replies. It is clear enough, though it never plainly restates 'mark thread as seen' and relies on the title for that framing.

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?

It gives an explicit exclusion: never record from a space_read_thread call that used regex or an author filter. It also states the authentication requirement. It does not fully spell out the positive trigger for when to call this versus other seen-marking tools, so it stops short of a 5.

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