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

Annotations only declare readOnlyHint=true; the description carries the rest of the behavioral burden: login plus organizer role required, only the activity's host/admins may read, the data contains contacts, and the letter content appears only in exported artifacts rather than the public activity page. It also discloses that the tool returns a version that downstream mutations depend on, which is the key interaction trait.

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 permission tag is front-loaded, followed by return contents, access rules, the workflow chain, and a privacy note, so the agent gets the essentials first. Density is high and nearly every clause carries information, though the sentence count is on the high side for a single-parameter read tool.

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 no output schema, the description compensates by listing what is returned (genre, formats, present and addable blocks, tips), and it adds auth requirements, the version/update/render workflow, and the non-public nature of the content. For a one-parameter read tool this is complete enough for correct selection and invocation.

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%, and the single `activity` parameter is already documented as an id or slug sourced from publish_activity_draft / list_my_activities. The description adds no additional meaning about the parameter beyond what the schema states, so the 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 (view one activity's invitation letter) and enumerates exactly what the read returns: current genre (formal/business/community), supported output formats, blocks already written, blocks still addable, tips. That enumeration differentiates it from nearby siblings such as get_activity_invitation_ledger, get_activity_invites and get_activity_agreement without the agent needing to open the schema.

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?

Explicitly names the two adjacent tools and the order of use (take version from this tool → update_activity_letter to edit → render_activity_letter to produce output), which is real routing guidance. It also gates usage to logged-in organizers/admins. It stops short of stating when this tool is the wrong choice (for example versus get_activity_agreement or preview_organization_invitation).

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