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

Goes beyond the annotations by disclosing the 1000-character limit, the null/empty-string clearing behavior (important for a non-destructiveHint tool that can still erase a value), and the downstream propagation to social platforms. Minor tension: idempotentHint=false sits oddly with a pure set/clear operation, though the description itself is not wrong.

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?

Three short sentences, front-loaded with the action, then the clearing rule and limit, then the downstream consequence. Every sentence carries information the agent cannot get from structured fields.

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 two-parameter mutation with no output schema and annotations covering the safety profile, the description supplies the operation, the clearing semantics, the size limit, and the effect on published posts. Nothing essential to correct invocation is missing.

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 already 100%, so baseline is 3, but the description adds real meaning: that both null and empty string clear the value, and the 1000-character ceiling that the schema does not state. It also clarifies what altText semantically is ("what it shows, for people who cannot see it").

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 ("Sets or clears the alt text of a picture in this project") and defines what alt text is, so the agent can distinguish it from get_media or update_brand_kit without reading schemas. The scope (a single picture's alt text) is unambiguous.

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?

Explains the operative context: the alt text ships to LinkedIn, X, Facebook and Instagram only when a post does not supply its own, which tells the agent when this value actually matters. It does not name alternatives (e.g. per-post alt text via edit_post) or state when not to call it, so it stops short of explicit routing.

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